Optical Fiber Sensors and Conventional Sensors

Optical Fiber Sensors and Conventional Sensors ABSTRACT This study deals with the comparison of the two types of sensors which are widely used in civil engineering, namely, conventional sensors and optical fiber sensors. Temperature and displacement are the two principal parameters which are measured with the aid of Fiber optic sensors. Bragg Grating, Interferometric, Intensity Sensors, and optical time domain reflectometry (OTDR) are some of the techniques which are used for sensing. In this study, various case studies have been undertaken and have been analyzed. With the aid of these case studies, a detailed analysis and comparison of the sensors is carried out. Chapter 1: INTRODUCTION In the last two decades, the world has witnessed a revolution in the sectors of optoelectronics and fiber optic communications. Various products such as laser printers and bar code scanners which have become a part of our daily usage, are a result of this technical revolution only. The reasons for the phenomenal growth of the fiber optics are many. The most conspicuous reason being the ability of the fiber optics to provide high performance and highly reliable communication links and that too at a very low bandwidth cost. As we see that optoelectronic and fiber communications industry has progressed a lot, and along with these industries fiber optic sensors have also benefited a lot from these developments. Due to the mass production in these industries, availability of fiber optic sensors at a low cost has been made possible in recent years. With their availability at affordable costs, fiber optic sensors have been able to enter the domain which was otherwise being ruled by the trad itional sensors. In recent years, the demand for the development of new materials to strengthen, upgrade and retrofit existing aged and deteriorated concrete structures has increased rapidly. The continuing deterioration and functional deficiency of existing civil infrastructure elements represents one of the most significance challenges facing the worlds construction and civil engineers. Deficiencies in existing concrete structures caused by initial flawed design due to insufficient detailing at the time of construction, aggressive chemical attacks and ageing of structural elements enhance an urgent need of finding an effective means to improve the performance of these structures without additionally increasing the overall weight, maintenance cost and time. In the last 50 years, a large number of civil concrete structures have been built; many of these structures, particularly in off-shore regions have now deteriorated and require repair in a short period of time. Moreover, the increase of traffic volume and population in many developing countries is causing the demand to upgrade existing concrete structures to increase. The damage of reinforced concrete (RC) structures through reinforcement corrosion and residual capacity are the most important issues that concern engineers. These problems occur not only in constructed concrete structures but also in structures strengthened by externally bonded steel reinforcements. In the past, the external steel plate bonding method has been used to improve strength in the tensile region of concrete structures with an epoxy adhesive and has proved to be successful over a period of 20 years. However, the use of steel reinforced plates and bars has its disadvantages including high corrosion rates, which could adversely affect the bond strength and cause surface spalling of the concrete, due to volumetric change in the corroded steel reinforcements. Since the early 1980s, fibre-reinforced plastic (FRP) materials have been used as a replacement for conventional steel materials for concrete strengthening applications. In recent years, the interest in utilizing FRP materials in the civil concrete industry in forms of rods, plates, grid and jacket has grown increasingly. When an FRP plate with high tensile strength properties bonds on the concrete surface, it can strengthen the structure with minimum changes to its weight and dimensions. FRP offers substantial improvement in solving many practical problems that conventional materials cannot solve to provide a satisfactory service life of the structure. Unlike the conventional steel materials, FRP is corrosion resistant. The beneficial characteristics of using the FRP in concrete construction include its high strength-to-weight ratio, low labour requirement, ease of application, reduced traffic interruption during repair, cost reductions in both transportation and in situ maintenance for a long-term strategy. Its high damping characteristic also attracts more structural engineers to use these materials for seismic retrofitting. Due to the increasing use of FRP-plate bonding techniques in strengthening civil concrete structures, the interest in finding a suitable means of monitoring the structural health conditions of these strengthened structures has therefore increased substantially. Since strengthened structures are covered by the FRP plates, the mechani cal properties of the concrete may not be measured or detected easily through conventional nondestructive evaluation (NDE) methods, such as strain measurements using surface mounted strain gauges or extensometers, radiography, thermography and acoustic emission methods, particularly in areas with microcracks and debonds underneath the externally-bonded plate. Besides, these structural inspection technologies, in certain cases, require special surface preparations or a high degree of flatness in the concrete surface. These requirements may be hard to achieve, particularly for an area that is exposed to a harsh environment. During the 1990s, a multi-disciplinary field of engineering known as ‘Smart Structures has developed as one of the most important research topics in the field.The structure is formed by a marriage of engineering materials with structurally-integrated sensor systems. The system is capable of assessing damage and warning of impending weakness in the structural integrity of the structure. Fibre-optic sensor technology is a most attractive device currently used in the aerospace and aircraft industry for on-line monitoring of large-scale FRP structures. The development of distributed fibreoptic sensors, which provides information on a large number of continuously distribution parameters such as strain and temperature is of great interest in most engineering applications.11,12 The sensors are embedded into a structure to form a novel self-strainmonitoring system, i.e. the system can self-detect its health status and send response signals to operators during any marginal situation during service. The embedding sensor, due to its extremely small physical size, can provide the information to a high accuracy and resolution without influencing the dimension and mechanical properties of the structure. Fibre-optic sensors present a number of advantages over the conventional strain measuring devices: (a) providing an absolute measurement that is sensitive to fluctuation in irradiance of the illuminating source; (b) enabling the measurement of the strain in different locations in only one single optical fibre by using multiplexing techniques;(c) having a low manufacturing cost for mass production; and (d) its ability to be embedded inside a structure without influencing the mechanical properties of the host material. A new development of ‘Smart materials and structures was driven by a strong demand for high performance over recent years. A system integrated into structures and being able to monitor its hosts physical and mechanical properties such as temperature and strain, during service is appreciated as a ‘Smart structural health monitoring system. The term smart material and structure is widely used to describe the unique marriage of material and structural engineering by using fibre-optic sensors and actuation control technology. The smart structure is constructed of materials that can continuously monitor their own mechanical and physical properties, and thereby, be capable of assessing damage and warning of impending weakness in structural integrity. This design concept results in improved safety and economic concerns regarding the weight saving and avoidance of over-designing of the structure in the long run. In Fig. 1, a schematic illustration of the structures possibilities created by the confluence of the four disciplines is shown. In the figure, a structure invested with actuating, sensing and neutral networking systems to form a new class of adaptive structures is shown. A structure with integrated sensor or actuator systems i s able to provide a self-structural health monitoring or actuating response, respectively. If both systems are integrated together into a structure, the sensor and actuators can act as nervous and muscular systems, like a human body, to sense the conditions such as mechanical strain and temperature of the structure (a smart structure) and to provide control of such changes of stiffness, shape and vibration mode (a controlled structure). The combination of these two systems into one structure is called a ‘Smart adaptive structure. This structure with a built-in neural networking system, like a brain, is then able to self evaluate the conditions, which are based on changes of structural parameters, thermal conditions and ambient environments to give an appropriate mechanical adjustment. This structure is commonly called an ‘Intelligent adaptive structure. 1.1 BACKGROUND OF THE STUDY There has been an unprecedented development in the fields of optoelectronics and fiber optic communications. This in turn, has brought about a revolution in the sectors of telecommunication and various other industries. This has been made possible with the aid of high performance and reliable telecommunication links which have low bandwidth cost. Optical fibers have numerous advantages and some disadvantages. The advantages include their small size, resistance to electromagnetic interference and high sensitivity. On the other hand, some of its disadvantages are their high cost and unfamiliarity to the end user. But its great advantages completely overshadow its minor disadvantages. So, in this study an attempt is being made to compare the modern age fiber optic sensors with the conventional sensors. Also, with the aid of the case studies, the impact of fiber optic sensor technology on monitoring of civil structures is studied (McKinley and Boswell 2002). 1.2 PROBLEM STATEMENT In the past various kinds of sensors have been used in civil engineering for measuring temperature, pressure, stress, strain etc. And as the optical fiber sensors spread their wings, the civil engineering is bound to gain a lot from these modern sensors. Presently, there exist a number of problems with the existing civil infrastructures. These civil infrastructures such as bridges etc. have a pretty long service period which may amount to several decades or maybe even hundred years. Thus, during this time period, these structures suffer from corrosion, fatigue and extreme loading. Since concrete is used mostly in these civil infrastructures, it degradation is a major issue all over the world. The amount of degradation and the time when the degradation starts depends on various factors and is inevitable and unavoidable. Thus, in order to keep these civil structures in good condition, it becomes necessary that their condition be monitored and adequate steps be taken. Thus, we need sensors which can monitor these structures throughout the life of these structures. Thus, in this study the impact of fiber optic sensors is studied on civil structures. 1.3 OBJECTIVES There are a few objectives that are planned to be achieved at the end of this project, these are: A general discussion on the present state of structural monitoring and the need of fiber optic sensors in this field A general study on Comparison between Conventional Sensors and Optical Fiber Sensors Review of Case Studies on Fiber Optic Sensors application in Civil Engineering Structures 1.4 WORK PLAN Discussion, reading and observation Problem identification through reading, discussion and observation of the area studied Understand and identify the background of problem Studying feasibility and needs to carry out the investigation Identification of the Title for the project Identify the aim, objective and scope of the project Literature Review Understanding the background of the problem Understanding the history of the sensor technology in structural monitoring Carrying out literature survey on generic technologies of sensors for concrete structures Identify the types of sensor involved in monitoring the structural in civil engineering Identify the technique used and the working principle for each type of sensors (in particular optical fiber sensors) Case Study Choose the relevant and related case study for discussion Describe important aspects of case study Analyze the use of sensors in the case study Discussion, Conclusion and Recommendations Discuss the similarities and differences Discuss the technical facets of sensor application Draw the overall conclusion for this project Give some recommendation for future Chapter 2: APPLICATIONS These days the fiber optic sensors are being used for a variety of applications, the most prominent of them being: Measurement of rotation and acceleration of bodies Measurement of electric and magnetic fields Measurement of temperature and pressure of bodies Measurement of acoustics and vibrations of various bodies Measurement of strain, viscosity and chemical properties of materials Measurement of surface condition and tactile sensing Measurement of sound , speed and proximity of bodies Determination of color and weight of different objects Measurement of linear and angular positions and this is widely utilized in civil engineering structures 2.1 ADVANTAGES OF FIBER OPTIC SENSORS Like with any other technology, there are both advantages and disadvantages using fiber optic sensors. The prominent advantages being: Fiber optic sensors are lightweight and this is of great importance in case of engineered structures Fiber optic sensors are of smaller size as compared to the traditional sensors Also, fiber optic sensors consume less power as compared to the traditional sensors Along with this, these sensors show high resistance to electromagnetic interference as compared to the traditional sensors On top of this, fiber optic sensors have enjoy high bandwidth and high sensitivity as compared to their traditional counterparts Fiber optic sensors are usually embedded in objects and due to this, these sensors can gain access to areas which till date remain inaccessible with the aid of traditional sensors Also, these sensors are accurate over a greater dynamic range as compared to the traditional sensors Fiber optic sensors are also capable of being multiplexed which again is a further advantage over their traditional counterparts Also, fiber optic sensors are capable of distributed measurements which gives them an edge over and above the traditional sensors Last but not the least, they also show greater environmental ruggedness as compared to the traditional sensors 2.2 DISADVANTAGES OF FIBER OPTIC SENSORS But all this is just one side of the coin. Though on seeing these advantages, it might appear that fiber optic sensors are way too advanced as compared to the traditional ones, but it is not exactly true. These fiber optic sensors also have some disadvantages due to which their advancement in todays world has been somewhat curtailed. The major disadvantages of fiber optic sensors are: Fiber optic sensors are quite costly as compared to the traditional sensors. Due to this, many people still consider traditional sensors to be a better option in cases where cost is a major consideration. Secondly, these sensors have come into prominence only in the last two decades. Due to this, people appear to be somewhat less educated regarding their usage and operations. And this unfamiliarity with the usage of these sensors, has proved to be a major hurdle in being able to capture the whole market. Also, these sensors are considered to be more fragile as compared to the traditional sensors which raises a question over their adaptability in extreme conditions Also with the fiber optic sensors there exists the inherit ingress/egress difficulty Fiber optic sensors usually have a non-linear output which is a cause for concern in some applications From the above discussion, we can see that as is the case with any other new technology, there are both merits and demerits of fiber optic sensors. But, what is worth considering here is that the advantages of this technology are much more than its disadvantages and are able to outweigh them. Also, from the demerits which are mentioned here, it is clear that these demerits are bound to wither away as this technology develops and gains more prominence. 2.3 APPLICATIONS IN CIVIL ENGINEERING Now we come to the discussion of the need and applications of the fiber optic sensors in the field of civil engineering structures. The monitoring of civil structures has a great significance in todays world. Today, we not only need to construct reliable and strong civil structures, but we also need to monitor these structures in order to ensure their proper functioning and their safety. Also, with the aid of the monitoring of various parameters of the structures, we can get knowledge about state of the building and by using this data, we can in turn plan the maintenance schedule for the structure (Mckinley, 2000). Also, this data can give us an insight into the real behavior of the structure and can thus take make important decisions regarding the optimization of similar structures which are to b e constructed in future. The maintenance of the structures can be approached in one of the two ways, namely: Material point of view- In this approach, monitoring is concentrated on local properties of the materials which are used in the construction. In this approach, we observe the behavior of the construction materials under the conditions of load, temperature etc. In this approach, short base length sensors are usually utilized. Also, it is possible to get the information about the whole structure with the aid of extrapolation of the data obtained from these sensors. Structural point of view- In this approach of measurement, the structure is viewed from a geometrical point of view. In this approach, long gauge length sensors appear to be the ideal choice. In this approach, we will be able to detect material degradation only if this material degradation has an impact on the form of the structure. In the recent years most of the research work which has been carried out in field of optic sensors has been in the field of material monitoring rather than structural monitoring. It is also worth mentioning here that, more sensors are required in the case of material monitoring as compared to structural monitoring. We know that civil engineering requires sensors that can be embedded in the concrete, mortars, steel, rocks, soil, road pavements etc. and can measure various parameters reliably. Also what should be taken into account is that these sensors should be easy to install and should not hamper the construction work or the properties of the structure in any derogatory manner. Also, it is common knowledge that at the sites of civil engineering, there exist the unavoidable conditions of dust, pollution, electromagnetic disturbances and of unskilled labor. Thus, the sensors to be used in these cases need to be rugged, should be inert to harsh environment conditions and should be easy to install and their installation could be carried out by unskilled labor. Along with all these things, it is imperative that these sensors are able to survive a period of at least ten years so that they can allow for a constant monitoring of the aging of the structure. Thus, we see that the fiber optic sensors ca n prove to be quite handful in civil engineering applications and structures. In the past various kinds of sensors have been used in civil engineering for measuring temperature, pressure, stress, strain etc. And as the optical fiber sensors spread their wings, the civil engineering is bound to gain a lot from these modern sensors (Vurpillot et al., 1998). Chapter 3: LITERATURE REVIEW ON FIBER OPTIC SENSORS Fiber optic sensors are of many kinds, but they can be broadly classified into two types, namely, extrinsic fiber optic sensors and intrinsic fiber optic sensors. There is a great deal of difference between these two types of fiber optic sensors and this difference is discussed in detail below. 3.1 EXTRINSIC FIBER OPTIC SENSORS This type of fiber optic sensor is also known as hybrid fiber optic sensor. As we can see in the figure above that there is a black box and an input fiber enters into this black box. And from this input fiber, information is impressed upon light beam. There can be various ways by which the information can be impressed upon. Usually this information is impressed upon the light beam in terms of frequency or polarization. This light which then posses the information is carried away by the optical fiber. The optical fiber now goes to an electronic processor. (Vurpillot et al., 1998) Here, in the electronic processor the information which is brought along by the fiber is processed. Though we can have separate input fiber and output fiber, but in some cases it is preferred to have the same fiber as the input fiber and the output fiber. 3.2 INTRINSIC FIBER OPTIC SENSORS The other type of optic fiber sensors is the intrinsic fiber sensors. An example of an intrinsic fiber sensor is shown in the figure below. The working of the intrinsic fiber sensors is somewhat different from the working of the extrinsic fiber sensors. In the intrinsic fiber sensors, the light beam is modulated and we rely on this modulation in the fiber in order to carry out the measurement. In the figure above, we can see an intrinsic fiber sensor or what is also known as all fiber sensor. 3.3 INTENSITY BASED FIBER OPTIC SENSORS While there exist various kinds of fiber optic sensors today, but the most common of these sensors is the hybrid type fiber optic sensor which depends upon intensity modulation in order to carry out the measurements (Zako et al., 1995) In the figure below, we can see a vibration sensor. In this vibration sensor, there exist two optical fibers. The functioning of this fiber optic sensor is quite simple. In this fiber optic sensor, light enters from one side. And when this light exits from the other side, it exits in the form of a cone and the angle of this cone depends on two parameters. The two parameters upon which the angle of this cone depends are: Firstly, it depends on the index of refraction of the core Secondly, it depends on the cladding of the optical fiber Also, the amount of light captured by the second optic fiber depends on a number of factors. The prominent factors on which the amount of light captured depend are: It depends on the acceptance angle It also depends on the distance â€Å"d† between the optical fibers Another type of fiber optic sensor is the flexible mounted mirror sensor. The important characteristics of this sensor are: In this case, a mirror is mounted which is used to respond to external parameters such as pressure. The modulation in intensity is caused the shifts in the mirror position. These sensors are used in a variety of applications such as door closures. In a door closure, a reflective strip is used. These sensors are used to measure small variations and displacements 3.4 LINEAR POSITION SENSORS In todays world, linear position sensors have become widely applicable. They are being used for various purposes (Zako et al., 1995). In many of the linear positioning sensors, wavelength division multiplexing is used. An illustration of the linear position sensor is shown in the figure below. The various components of this linear position sensor are: It consists of a broadband light source It consists of various detectors as shown in the figure above It also consists of wavelength division multiplexing element which acts as the principal component of this instrument. It also consists of an encoder card In the example above, a broadband light source is utilized. The light from this broadband source is carried to a wavelength division multiplexing system with the aid of a single optic fiber. The wavelength division multiplexing system is used to determine the linear position. Another linear motion sensing method which is very widely used today and is quite similar to the method discussed above is known as the time division multiplexing method. This method is illustrated with the aid of a figure shown below. In this method instead of a broadband light source a light pulse is used. Here, the combination of the returned signals takes place. As a result of this combination of the returned signals, the net signal which is produced moves onto the position of the encoder card. The main areas in which these intensity based fiber optic sensors have found application are: In commercial aircrafts In military aircrafts In these applications these modern sensors have performed quite well and are at par with the performance of the conventional sensors. But, because of the various advantages these sensors enjoy over and above the conventional sensors, these modern sensors are bound to replace the conventional sensors in the years to come. 3.5 LIQUID LEVEL SENSORS This is another type of intensity based fiber optic sensor. In the functioning of this sensor, the principle of total internal reflection is utilized. Thus, in these sensors the refraction index of the glass and the fiber occupy the pivotal role. These sensors can be utilized for a variety of purposes. The most prominent of its applications are: Measurement of pressure changes in gels Measurement of pressure changes in various liquids Measurement of refractive index changes in gels Measurement of refractive index changes in different types of liquids Measurement of the level of a liquid in a vessel and this application is utilized in various industries to measure liquid levels These sensors have an accuracy of about 5 percent and are gaining importance in various industries for their usefulness. 3.6 SOFO SENSORS These are fiber optic sensors which are utilized for strain measurement. These sensors have become quite popular owing to their innate merits. Out of all the fiber optic sensors, these sensors are the ones which are being used most extensively today. These sensors are being used to measure curvature and various other parameters in giant civil structures. These sensors form a part of the interferometric system (Vurpillot et al., 1998). Also, these sensors have the ability of measuring the parameters in an absolute manner using low-coherent light. The important properties of these sensors are: These fiber optic sensors enjoy a high resolution. The resolution of these sensors is 2  µm These sensors can be of varied lengths. Their length can be as small as 0.2m or can be as large as 20m. Also, these sensors have the property of being temperature compensated The SOFO system setup consists of a number of equipments. The main components of the SOFO system setup are: It consists of a fiber optic sensor which forms the crux of this monitoring system. It is the most important component of the monitoring system. It consists of a sensor chain with partial reflectors. One terminal of this sensor is connected to the coupler Another terminal of the sensor chain with partial reflectors is connected to the LED. The coupler in turn is connected to the photo diode and a mobile mirror. This whole portable reading unit is connected to portable computer terminal. This ensures that that the whole monitoring system can be taken to the location and can be directly used at site. These sensors can be utilized in two ways. They can either be embedded in the structure at the time of the construction of the structure. Or, they can used to measure the various parameters externally. Though in both the cases, that is, in case of embedding or in the case of external anchoring, the performance of the sensors remains the same, but still, in modern smart structures, embedding is preferred (Perez 2001). This is because, in the case of embedded sensors, the sensors continuously measure the parameters and are easy to manage. Whereas in the older structures, where embedding is not preferred, external anchoring is used. Chapter 4: CASE STUDIES Case study 1: Monitoring of San Giorgio pier San Giorgio pier is a massive concrete structure. Its length is about 400metres. It

Consider carefully which of Bathsheba Essay

TASK: Consider carefully which of Bathsheba’s three suitors, Boldwood, Troy or Oak possessed the qualities most likely to make Bathsheba a good husband. In the book, ‘Far from the Madding Crowd’ by Thomas Hardy, there are three suitors for the novels protagonist, Bathsheba Everdene. Unfortunately because she is a very capricious lady, one suitor is murdered by another, who was consequently sentenced to life imprisonment. This essay will discuss which suitor would have been the most compatible to Bathsheba in marriage. In the novel, Bathsheba is the second character we are introduced to, and Thomas Hardy portrays her as a very beautiful but penniless woman. She is the protagonist of the novel, and her interaction with her various suitors propels the plot. As the story unfolds, her character is developed, but it is very clear in the beginning she is a very vain woman. This is firstly shown when Gabriel sees her sitting on top of a carriage full of furniture. It is obvious her beauty entrapped him and he, ‘followed the vehicle to the turnpike gate some way beyond the bottom of the hill, where the object of his contemplation now halted for the payment of the toll. ‘ Bathsheba’s vanity was evident where she refused to pay the turnpike keeper the extra two pence he wanted. Subsequently, Gabriel paid it and she was neither pleased nor dismissive because she had lost her point, she was just a little disgruntled. In addition to this, shortly after she is seen looking into her mirror, admiring herself. Further reference to Bathsheba’s vanity is later in the story when she has just inherited the farm and she throws all of her existing clothes away because she feels she has moved up a class, and her old ones were inferior. The last evidence of her vanity occurred after she had encountered Troy for the first time, when she was in front of her dressing table mirror and she repeated a sentence he had whispered to her, ‘Hello gorgeous’. Despite this flaw in her character, she showed independence in both financial and spirited terms. She was able to run the farm she had inherited by herself, and after finding her bailiff stealing grain, she fired him and took on that job as well. Furthermore, having moved up a social class didn’t seem to effect this self-reliance as she still travelled to Bath on her own not asking for a chauffeur to ride the cart for her, as most rich people would have because of their status. She wasn’t accompanied by anyone when she went out horse riding either. This shows both independence and that she likes to be alone sometimes, not in the eye of her employees. There are many other of her characteristics which are described in the novel, including bravery which is highlighted on three occasions: in the beginning of the novel where she saves Gabriel from gas poisoning in his hut; when she helps Gabriel to secure the hayricks in the storm and the way she dealt with the numerous disasters on her farm. One of those disasters was bought on by her impetuousness as she fired Gabriel because he rebukes her, saying ‘I cannot allow any man to – to criticize my private conduct!†¦ Nor will I for a minute. So you’ll leave the farm at the end of the week! ‘ From this it is obvious she is intolerant towards gossip and people’s views. Unfortunately, shortly after Oak leaves, a disaster happens, whereby the sheep all get a disease, which only Oak knows how to treat. Subsequently she has to swallow her pride to save her sheep. A further example of her impetuous character was a little later on in the novel, when she visited Bath and married Troy so that his attentions would only be focused on her, and not any other women. This also shows immaturity in her, not just the rash decision of marriage, but also the quick dismissal of Oak because she couldn’t take criticism. Contrary to this though, when Fanny went missing, she was responsible enough to send out a search party, so despite being volatile and distant from her workforce, she was still interested in their well being, even though she was an x-employee. No later than Troy goes missing, she turns to Boldwood who she had previously sent a valentine to, admittedly quite reluctantly, but she does, and this highlights the capriciousness and flirtatious side of her character. This isn’t a good thing for a relationship, especially in a vain woman like Bathsheba, who would be easily convinced to see other men, so a compatible partner for her would have to be stern with her, but in a loving manner. Therefore, the best suitor for Bathsheba needs to be able to cope with the characteristics I have highlighted above, being similar to some of her characteristics, and the opposite to others. The best person for her would be a handsome and romantic farmer who was financially secure. Mr Boldwood is the wealthiest of the three suitors whom Bathsheba could have chosen, owning a neighbouring farm. As his name suggests, he is quite a wooden man. By this I mean he doesn’t reveal his true emotions until he is sent the valentines letter on a whim when he suddenly develops feelings for her. From this point onwards, he loses his self-control and pursues her with a single-minded passion to make her his wife. Unfortunately, because his love becomes so all-compassing and single mindedness, it leads him to neglect his farm losing all of his crop one stormy night. He is also quite a personal and reserved man who, despite many women finding him attractive, lives a quiet life on his neighbouring farm. His high status in society is indicated on numerous occasions, but the most obvious occurrence was when Bathsheba invited Mr Boldwood over to join in the celebratory dinner after the successful harvest. At first Gabriel Oak, Bathsheba’s main shepherd was sitting at the head of the table, but when Mr Boldwood appeared a little later, Gabriel was asked to move from the head of the table so Mr Boldwood could be seated. It is obvious from the moment Mr Boldwood starts to develop feelings for Bathsheba that he is a caring man, always checking up on her, but it is later on in the story when Mr Boldwood’s chivalrous side is shown to its full extent. Bathsheba had been seeing Troy for a little while, and they were having relations outside of marriage, which for the novels time was not allowed. Therefore Mr Boldwood offered Troy money to marry her, in order for her name to be respected. This was obviously a very hard act to come to do, especially as he loved her so dearly. When Troy went missing, believed drowned, Bathsheba was in mourning for a little while, but because no body was found, she had to wait seven years before she could marry again. Mr Boldwood made his feelings clear to her again a little later, and she agreed upon marriage if Troy didn’t reappear after seven years had passed. This showed a very patient side of Boldwood, different to the very persistent side of him seen earlier in the book. Unfortunately, after seven years had passed, on the night Bathsheba had promised to accept Boldwood’s proposal, Troy burst into the party, insisting on regaining his half of her farm, which came with the marriage. At first Boldwood was deeply upset, but knew there was nothing he could do about it and accepted it, but Bathsheba refused to go at first, and Troy rough handled her. Boldwood, did not like, or accept this, especially because he was so protective and obsessed with her. A mixture of jealousy and over protectiveness then took hold of him, and he shot Troy, killing him almost instantly. Boldwood was then sentenced to death, but because of his high status, because he was a well-respected gentleman and finally because it was argued he was mentally unstable, the sentence was changed to life imprisonment. After the sentence was passed, his obsession with Bathsheba was revealed to its full extent, as items of clothing and jewellery were all found in Boldwood’s house, all gift wrapped and with a label saying ‘Bathsheba Boldwood’. Sergeant Troy is the second of Bathsheba’s possible suitors. Troy is the novels antagonist, and is the less responsible male equivalent of Bathsheba, and his description is the complete opposite of Gabriel Oak’s. His irresponsibility is shown on the night of the ‘after harvest celebratory meal’ when he decides to get drunk, knowing there is a storm which could destroy all the hayricks which they had just harvested. Unfortunately, because he was devastatingly attractive, had a dashing manner, continually flattered Bathsheba and was skilled in swordsmanship, she fell for him. This was mainly because of her vanity; he said what she wanted to hear. And furthermore, it was his vanity which made him say such things as, ‘Thank you for the sight of such a beautiful face’ and ‘Ah, beauty; good-bye! ‘ This first impression of Troy gives him the appearance of having some strength of character, such as helpfulness when he offers to help in the haymaking when he bumps into Bathsheba one night. Unfortunately, this strength in his character is quickly shown to be limited, for example, he initially gave the impression of being frank, letting his thoughts be heard, but this is quickly offset by his lies. Troy lied on numerous occasions, such as when Bathsheba saw a lock of golden hair in Troy’s pocket watch, when he said he went to church regularly through the back door, which when investigated by Gabriel was found to have not been opened for a very long time and thirdly when he said he didn’t know the tramp on the road. It was in fact Fanny Robin who he was engaged to, but neglected after they miscommunicated about which church they were due to have their marriage in. She was actually Troy’s true love and the lock of hair in his pocket watch belonged to her. Another act, which showed Troy’s character to be limited, was the way he acted and cruelly abused her after they were married. This really shows that Troy was quite capricious in a way because no later than Troy has left Fanny, he seduces Bathsheba. Troy was an unstable character, mainly because when his parents died when he was only small, he was sent off to be a soldier. This environment, which he grew up in, therefore influenced his character, and he became a mercenary, working only because he wanted to spend money at the races. Unfortunately, not being trustful, he left Fanny gambling debts, and he used a lot of Bathsheba’s money up as well. Another quality of Troy’s was his cunningness and deviousness. This is shown near the end when, after seven years of being missing, presumed dead, he returns, not for Bathsheba, but for the money which he was entitled to, namely half Bathsheba’s assets (farm and contents) which came with getting married. That was what triggered Boldwood to kill Troy in the end, the way he was only interested money, and the way he mishandled her. The third and final suitor was Gabriel Oak. He was in fact the first of the three men whom Bathsheba met in the novel when he generously paid the two pence toll for her because she felt she had already paid enough. The novel starts describing Gabriel; ‘When Farmer Oak smiled, the corners of his mouth spread till they were within an unimportant distance of his ears†¦ ‘ He isn’t the best looking of men, and is only a shepherd, but has a very strong, good character, which is developed throughout the novel. Being a shepherd, he has exceptional skill with animals, and is hardworking. He knows the trade so well that he can tell when it is going to be bad whether and acts accordingly. An example of this was when the storm came after the hayricks had been harvested and, knowing a storm was on its way, Oak tried to alert the others for help, but after realising they weren’t interested, he started tying them down on his own. This shows determination, responsibility and reliability. Whenever Bathsheba needed help, he would be there, even after he had been dismissed for criticizing her judgement, he forgave her and came back to save the sheep from a deadly disease. Another example of his responsibility was when Joseph Poorgrass stopped off at the Buck’s Head Inn for a drink, rather than taking Fanny’s coffin to the church. It was Gabriel who went to the inn and too the coffin to the church, and then on to Bathsheba’s house because Joseph had delayed them so much. When he saw Fanny’s coffin, he was generous in spirit, because he rubbed off ‘and baby’ after Fanny’s name because he wanted to spare Bathsheba’s feelings, especially as it was Troy’s baby. The reason Bathsheba said that she would not marry him when he asked was because he wasn’t that rich and he was unromantic, which is a characteristic in Oak which Bathsheba would have wanted from her husband. Shortly after, he unluckily lost all of his sheep, but instead of reverting to alcohol, or committing suicide, he put it behind him, paid off his debts with what he had left, and went to the market to look for a job. While this is all occurring, he is still steadfast, wanting to marry Bathsheba, and he is loyal, not going after any other women. Instead he just concentrates on his work, and is as hardworking as ever, in a sense he is quite boring because he doesn’t ease up on his work. Even when she marries Troy, he is thoughtful, sparing her feelings, as she is not aware of all the truth. His loyalty, whether standing up for Bathsheba when the workers gossip, or just by being there for her, is repaid later when Bathsheba finally gives him the job of Bailiff. It is mainly because of his organised nature, and because he has a very good knowledge of the farm. In conclusion, I have to answer the original question, ‘Consider carefully which of Bathsheba’s three suitors, Boldwood, Troy or Oak possessed the qualities most likely to make Bathsheba a good husband. ‘ After analysing each of their characters, I feel she would really be best off with a person who had parts of each of the suitors: Boldwood’s money and devotion, Troy’s handsome appearance and Gabriel’s knowledge of farming. Unfortunately this is impossible, therefore I have chosen Gabriel Oak as whom I feel would be the best suitor for Bathsheba Everdene. I think that despite Boldwood saying that she would never have to work again, she is a very independent woman, and I’m not sure she would appreciate that. Troy is like the male equivalent of Bathsheba, and I don’t think that she would last that long with him, as problems would arise. Furthermore, he mishandles her, and I think their marriage would be over very quickly. Gabriel is quite different to Bathsheba, and I think that he would be devoted to her, especially after analysing his character, but wouldn’t smother her, still giving her her independence. Furthermore, his knowledge of farming would be helpful on the farm. Marriages last if the couple can communicate, and come to a conclusion about situations, and I feel Boldwood would just do whatever she wanted to do, Troy would only do what he wanted to do, but Oak would do whatever was best and fair. Gabriel’s character is opposite to Bathsheba’s, but in this case I think the marriage would work really well.

Why The Red Orchestra Was An Agent For Russian...

Despite his humble background, this mastermind, a man who had â€Å"never taken a course in espionage†, was able lay the roots for an anti-Nazi spy network in 1939 that would become one of the most expansive and powerful espionage organizations ever to exist. Leopold Trepper, originally an agent for russian intelligence (GRU), directed seven networks within the organization, known as the â€Å"Trepper Group†, which was spread throughout Germany, France, and Belgium. The Trepper Group soon joined with two other spy networks: the Schulze-Boysen/ Harnack group in Berlin, and the Red Three in Switzerland (which was closely affiliated with the Lucy Spy Ring, another anti-Nazi network in Switzerland). Together, they wreaked havoc upon the Nazi empire for the entirety of WWII, eventually earning the name â€Å"The Red Orchestra† from the Gestapo. The Red Orchestra was able to contribute to the eventual fall of the Nazi Regime by helping many people targeted by the Nazis to escape to safety, promoting anti-Nazism and resistance, and most importantly, stealing and intercepting German intelligence and giving it to the Allies. One approach the Red Orchestra took for saving the Jews was to personally harbor them and transport them out of the Nazi territory. The organization, specifically the Schulze-Boysen/ Harnack group, established an Underground Railroad of sorts, and they would rescue anyone who was being targeted by the Nazis, mostly Jews, and help them to safely get out of the country before

A Brief History of American Imperialism - 1391 Words

The United States saw its territory more than double in the first three decades of the 19th century. Bursting with nationalist fervor, an insatiable desire for more land, and a rapidly increasing population, the western frontiers of the United States would not remain east of the Mississippi. The eventual spread of the American nation beyond the Mississippi into Native and French land, referred to as â€Å"Manifest Destiny† by John O’Sullivan, was rationalized as a realization of their God given duty. The Louisiana Purchase set the precedent for unrestricted westward expansion in America, and allowed for others to follow in his footsteps. Characterized by racist overtones, a lack of the â€Å"consent of the governed, and ethnic cleansing, there is no†¦show more content†¦During the presidency of James Madison, the question of what to do about Spanish controlled Florida came to the forefront. Florida would be of immense importance for both the protection of the United States from Spain, and for the access it would give to the Gulf of Mexico for trading ports. Recognizing this, Madison instructed John Quincy Adams, then Secretary of State, to being negotiations with Don Luis de Onà ­s, Spanish Minister to the United States, on the exact borders between U.S. and Spanish territory. However during these negotiations, future president and General, Andrew Jackson invaded Florida. When Onà ­s protested to this invasion, it was rebutted by Adams that, â€Å"Florida had long been a refuge for hostile Indians, runaway black slaves, and outlaws [†¦] the U.S. might be forced to seize the territory as a matter of self-defense.† It also showed that the forced seizure of the land could be swiftly accomplished at any time. 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