Information and knowledge in technology Essay Example | Topics and Well Written Essays - 3250 words

Information and knowledge in technology - Essay Example Such information flow cannot be regulated by the government. Search engines have evolved into very efficient machines today. The first search engines did not meet the needs of the average person. Searches yielded irrelevant information. Companies paid search engine companies to show their websites whenever a customer searched for a certain word or group of words. For example, when a person searched in Yahoo for the word â€Å"car," BMW was among the first websites to appear even before a website that defined the word â€Å"car" (Battelle, 2005). While such advertising models were beneficial to businesses, customers hoped that an efficient search engine would be created. People wanted a tool that would help them get information fast. When Google was created, it answered most of the customer’s needs. First of all, the philosophy that drove the creation of Google was to organise all the information of the world so that people could easily search and get it. The company refused to follow the model of Yahoo and other search engines. In fact, it took some time before Google thought of a way of monetising the search engine. Deep down their hearts, they wanted to help people out. It is the reason Google is the number one search engine on the planet. Other companies followed the model set by Google, so included Microsoft with Bing. Google and other modern search engines earn money through advertising. They use pay per click model whereby all the adverts that appear after the customer searches for information depends on what the customer has looked. It is not a random system. Social media is another method through which people get information. Human beings are social and they do not live in isolation. The fact that people can connect and communicate with loved ones post photos and content such as music and video have revolutionised the way we live. Companies such as Facebook and Twitter facilitate massive transfer of information for people who have signed up for

Business Environment Analysis of British Airways Essay - 1

Business Environment Analysis of British Airways - Essay Example The assessment of the external environment is conducted in reference to its impact on British Airways. For the purpose, the range of strategic management tools has been employed. British Airways (BA) is a private limited company is renowned airline that has recently celebrated 90 years of existence in the year 2009. It is one the leading premium airlines of the world and the largest airline of UK and covers around 400 destinations across the world (British Airways, 2013). The business model of BA is based on the revenue generation from the passenger as well as cargo delivery services. With the long rich history and experience, BA has become one of the leading airlines that have extensive scheduled flights and network of airline. Additionally, it is a comprehensive list of joint agreements, franchise partners and other defined codes that enables it to service wide network of stations (airports). Importantly, in the year 2010, BA merged into Iberia which is the largest airline of Spain (British Airways, n.d.). British Airways generate its revenue from the two basic sources including passenger revenue and the cargo revenue. For the year 2013, BA generated revenue of around  £ 10,129 million from the passenger revenue with the growth of 6.6% while the cargo revenue declined by 6.5% and generated  £ 689 million in 2013 as compared to 2012. The year 2013 was driven by considerable investment in the airline with constant focus on expanding customer base along with the cost reduction measure at effect (British Airways, 2013). This section of the report will produce the information related to the British Airways. The information will be specific to the business direction and future vision of the business along with impact of the external environment on BA and its response. The mission of British Airways, as reported in the marketing in magazine, is â€Å"to serve† (Eleftheriou-Smith, 2011).

Why Stalin emerged as the dominant political force by 1929 Essay Example for Free

Why Stalin emerged as the dominant political force by 1929 Essay A ruthless tyrant (Totsky), Stalin built up power within the Bolshevik party, at first quietly and almost unnoticeably, but then used the combination of his position to assure him almost limitless powers. He removed his opposition step by step tactically switching sides of the party, and thus clearing his way up to the top. Essentially Stalin emerged the dominant political force by 1929 because he removed all opposition from the party making him the prime leader of the party. Stalin held a number of what at first seemed as insignificant posts, which later gave Stalin as extensive amount of power within the party. His titles were Commissar of Nationalities (1917), Chairman of Orgburo (1919), Chairman of Workers and Inspectorate (1919) and later General Secretary of the Party (1921). With these posts Stalin had access to personnel files on all of the party members. Due to the structure of the party at the time this unintentionally gave him prerogative, as he became the indispensable link in the chain of command. Stalin also gained the right to appoint and withdraw individuals to/ from official positions within the party. He used this to his advantage and appointed his own people, (ie: those who were loyal to Stalin and followed the same ideology as him,) in key positions. Stalin therefore replaced individuals from key positions and replaced them with his supporters. This in result gave him overwhelming power as he could count on these people to vote for him and therefore no matter the ability of the individuals or groups that opposed him, he could always out-vote and out-manoeuvre them. Hence Stalin could now influence the party leading to him becoming a dominant political force by 1929. Starting from 1923 Lenin decided to increase the membership of the party with more industrial workers, which carried on until 1925 and was known as Lenins Enrolment. Over 500,000 workers were recruited, doubling the partys membership and this was to have important consequences. The new members were largely uneducated and politically naà ¯Ã‚ ¿Ã‚ ½ve. As a general secretary, it was Stalin who was responsible for supervising Lenins Enrolment. E.H. Carr pointed out that the Bolshevik Party changed from the elite party of Lenin to the mass party of Stalin. Stalin was therefore building prodigious support, later leading to him becoming the dominant political force in Soviet politics. Stalin was also strengthened unintentionally by Lenin and his attack on the Factionalism. Lenin condemned the party squabbling and the opposition to party from within the party. Lenin effectively quelled and frustrated any serious attempt to reprehended party policy or decisions. This made it increasingly difficult to form legitimate opposition from within the party. This bourgeoned Stalins power as firstly he was a beneficiary of the attack on factionalism and the charge of factionalism provided him with a ready weapon for resisting challenges to the authority he had already began to exercise. This was one of the tactics employed by Stalin to secure him the next successor to Lenin. Due to these tactics Stalin emerged as the dominant political force by 1929. The party was divided among many issues with the New Economic Policy having the greatest significance. Those who were critical of the NEP were branded left communists and those who accepted that as long as the NEP continued to meet the nations food needs then it should be preserved, were branded right communists. Stalins view was that a rivals attitude towards the NEP might be weakness to be exploited; if it could be established that his views indicated deviant Marxist thinking it becomes possible to undermine, if not destroy, his position within the party. Stalin therefore switched sides of the party by switching sides of the argument to undermine his rivals step by step. Therefore his rivals would loose credit while he would gain credit. However the main and most notorious tactic used by Stalin was to keep his political status within the party centre. This way Stalin could easily move from left to right to weaken and plot against his rivals. The Politburo saw Trotsky as a grater danger than Stalin. Stalin therefore first formed triumvirate with Zinoviev and Kamenev to block Trotsky, who was soon accused of criticising the Cult of Lenin and his absence in Lenins funeral was made to be seen as heresy. The new proletarian membership helped Stalin to remove Trotsky as the party was not impressed by the cultured image of Trotsky. As a result Trotsky was outvoted in 1927, which led to congress accepting the proposal that Trotsky is to be expelled from the party and was soon internally exiled. As his next step, Stalin used the fact that Zinoviev and Kamenev sided with Trotsky over the issue of NEP against them and to also get them out of his way. Stalin moved to support the right of the party, who believed in NEP as a saviour of Russias present economy. In result, the 1925 party congress defeated all left wing motions and denounced the lefts as traitors of the revolution. Hence Kamenev and Zinoviev were exiled from the party. After the left of the party had been defeated Stalin started work to defeat the right of the party. After two good harvests at the end of 1925 Stalin used the argument that grain prices were falling as peasants were withholding grain to force up the price of grain. Stalin saw this as capitalism at the expense of the cities. He introduced a criminal law causing the concealment of grain to be a crime. He sent soldiers into the countryside to punish the peasants, This led to fighting in some areas and Bukharin in result denounced Stalin as a tyrant. Bukharin and his followers were condemned as right-wing deviationists. At the end of 1928 Bukharin resigned as editor of Pravda and along with Trotsky and Rykov they were expelled from the party. Therefore now Stalin had successfully removed the opposition from both sides of the party, filling the gaps in the party with his followers and in result leaving him as the only political force to rule the Soviet Union. In conclusion Stalin destroyed his opposition in order to leave him as the only obvious candidate to succeed Lenin as the leader of the Bolshevik Party. Stalin rose to power using his strategic position as the General Secretary to his advantage. The structure of the party also benefited him as his actions did not seem to be that significant in his fight for power at first hand and therefore hiding him from condemnation.

Calculations of Rare Earth (Y, La and Ce) Diffusivities

Calculations of Rare Earth (Y, La and Ce) Diffusivities First-principles calculations of rare earth (Y, La and Ce) diffusivities in bcc Fe Xueyun Gaoa,b,[*], Huiping Rena, Chunlong Lia,c, Haiyan Wanga, Yunping Jia, Huijie Tan a ABSTRACT: The impurity diffusivities of rare earth elements, Y, La and Ce, in bcc Fe have been investigated by the first-principles calculations within nine-frequency model. The microscopic parameters in the pre-factor and activation energies have been calculated. For the three elements, the first nearest-neighbor solute-vacancy interactions are all attractive, in which Y and La solute atoms more favorably bond to the vacancy. The solute-vacancy binding energy can be explained in terms of the combination of the distortion binding energy and the electronic binding energy, and the decomposition results of the total solute-vacancy binding energy suggest that the strain-relief effect accounts for larger portion of the binding energy for Y and La than that for Ce. The diffusion coefficients of Y are one order of magnitude larger than that of La, and predicted to be comparable to that of Fe self-diffusion. Compared with Y and La, Ce shows large migration energy and small solute-vacancy att ractive interaction, which accounts for the lowest diffusivity of this element. Keywords: Diffusion; Rare earth; Bcc Fe; First-principles calculations 1. Introduction In the past years, the addition of rare earth (RE) elements has been regarded promising in steels. A series of beneficial research for the development of rare earth addition have been focused on the purification and modification of inclusion, since RE elements are characterized by significant negative free energy changes for compound formations [1-3]. RE doping also improve the high-temperature oxidation resistance and the corrosion resistance of steels due to the reactive-element effect (REE) [4,5].In addition, the solidification, phase transformations, recrystallization behavior, of steel can be improved by adding RE [6, 7]. Knowledge of the above mentioned mechanism is essential to understand the influence of RE additions on the physical, chemical and various properties of steels. In spite of the progress so far in RE application, it is apparent that many questions still remain rather controversial. A thorough theoretical study on the diffusivities of RE elements in Fe-based alloy is still lacking, which is essential for understanding the effects of RE on the structure and properties of steel, and is also helpful for designing and preparing RE doped steels [8]. For the three commonly used RE elements, Y, La and Ce, to our knowledge, only the diffusion coefficient of Y has been reported [9]. The diffusion of substitutional-type solute is mainly controlled by vacancy mechanism. In this case, the interaction of solute atom with vacancy plays significant roles in understanding of the diffusion properties of solutes. To understand the microstructure evolution in bcc Fe alloy, DFT method has been applied in calculations of the binding energies of solute atom with vacancy [10]. Based on the nine-frequency model of Le Claire, Ding and Huang et al. [11,12] developed a computational framework to calculate the solute diffusion coefficients in bcc Fe, which presents an effective method in investigation of the diffusion properties in bcc Fe alloy. The purpose of this work is to investigate the impurity diffusivities of rare earth elements, Y, La and Ce, in bcc Fe by the first-principles calculations within nine-frequency model and the semi-empirical corrections for magnetization[11,13], calculate the associated solute-vacancy binding energies, migration energies, pre-factors and activation energies for these impurity diffusivities, as well as the self-diffusion coefficient of Fe, thus discuss the related factors of the diffusion coefficients. 2. Methodology The temperature dependence of diffusion coefficient D is expressed in the Arrhenius form D=D0exp(-Q/kBT), where D0 and Q are the pre-factor and activation energy, respectively. Below the Curie temperature, the self-diffusion and solute diffusion coefficients in bcc Fe deviate downward from the Arrhenius type relationship extrapolated from the paramagnetic state [14]. These deviations are attributed to the change of magnetization which affects the diffusion activation energy. To investigate the effect of magnetic disorder on the diffusion activation energy of spin-polarized metals, Ding et al. [15] reported a first-principles approach based on the spin-wave DFT method for studying the self-diffusion of bcc Fe and fcc Co, and the calculated values of ÃŽÂ ± agree well with the experimental data. More recently, by combination of the first-principle calculations and Heisenberg Monte Carlo simulations, Sandberg et al. [16] presented a quasi-empirical model to study the magnetic contribu tion to the self-diffusion activation energy of bcc Fe. Murali et al. [17] conducted a systematic study of the effects of phonon and electron excitations on the free formation energy of vacancy, the solute-vacancy binding energy, and the vacancy migration energy in bcc Fe. The authors then calculated the Fe self-diffusion coefficient based on the computed free energies, by employing the semi-empirical model presented in Ref. [18]. The diffusion associated data yielded by these methods are in good agreement with experiments. We employ the semi-empirical model to describe the dependence of the diffusion activation energy on the magnetization in the ferromagnetic state [18]: QF(T)=QP[1+ÃŽÂ ±s(T)2] (1) where QP is the activation energy in the paramagnetic state; s(T) is the ratio of the magnetization of bcc Fe at a certain temperature T to that at 0K, and has been experimentally measured [19,20]; the constant ÃŽÂ ± quantifies the extent of the influence of magnetic on activation energy, the measured value of ÃŽÂ ± for Fe self-diffusion is 0.156 [11].In the case of the solute species investigated in this context that have no measured ÃŽÂ ± values available, the values can be estimated from a linear correlation with the induced changes in local magnetization on Fe atoms in the first and second neighbor shells of a solute atom [21]. The first-principles calculations give direct access to the magnitude of the activation energies for self- and solute diffusion in the fully ordered ferromagnetic state (T=0K). Given the values of ÃŽÂ ± and s(T), we can compute QP through the relation , and QF(T) from Eq. (1). We based the diffusion calculations on the assumption that the mechanism of diffusion is primarily monovacancy mediated. The self-diffusion and solute diffusion coefficients on a bcc lattice can be expressed as following [11,22]: Dself=a2f0Cvw0 (2) Dsolute=a2f2Cvw2(-ΆGb/kBT) (3) where a is the bcc lattice constant, f0=0.727 is the self-diffusion correlation factor, f2 is the correlation factor for solute diffusion which depends on the relative vacancy jump frequencies around the solute atom. Cv denotes the equilibrium vacancy concentration, can be written as Cv=exp(ΆSf /kB)exp(-ΆHf /kBT), where ΆSf and ΆHf are the vacancy formation enthalpy and entropy, respectively, the harmonic approximation makes these two become temperature-independent constants. and kB is Boltzmanns constant. w0 and w2 are the vacancy hopping frequencies for Fe and solute atoms to exchange with a nearest-neighbor vacancy, respectively. Based on transition state theory (TST), the vacancy hopping frequency w is written as , where and are the phonon frequencies in the initial state and transition state, and the product in the denominator ignores the unstable mode; ΆHmig is the migration energy, gives the energy difference for the diffusin g atom located at its initial equilibrium lattice position and the saddle-point position. The solute-vacancy binding free energy ΆGb can be expressed as ΆGb =ΆHbTΆSb, where ΆHb and ΆSb are the binding enthalpy and entropy, respectively. The correlation factor f2 can be calculated using the nine-frequency model developed by Le Claire [13] which involves different jump frequencies of vacancies to their first neighbor position in the presence of the solute atoms, as illustrated in Fig. 1. In this model, the interaction of solute-vacancy is assumed up to second neighbor distance. The nine frequencies shown in Fig. 1 illustrate all of the distinct vacancy jumps in a bcc system with a dilute solute concentration, including the host Fe atom jump w0 without impurity. The detailed calculation procedures could be found in Ref. [11]. Fig. 1. Schematic illustration of the nine-frequency model for the bcc Fe crystalline with a solute atom. The arrows denote the jump directions of the vacancy. The numbers in the circle represent the neighboring site of the solute atom. For convenience, we can represent the self- and solute diffusion equations (Eqs.(2) and (3)) in Arrhenius form to obtain the pre-factor and activation energy of diffusion. By combining the above Eqs., the diffusion coefficient for Fe self-diffusion and solute diffusion can be expressed as: (4) For self-diffusion, the pre-factor is, and the activation energy given as . Also, the solute diffusion coefficient can be expressed in an Arrhenius form with the pre-factor is, and. The first-principles calculations presented here are carried out using the Vienna Ab initio Simulation Package(VASP) with the projector augmented wave(PAW) method and the generalized gradient approximation of Perdew-Burke-Ernzerhof functional(GGA-PBE) [23]. All calculations were performed in spin polarized. The computations performed within a 4à ¯Ã¢â‚¬Å¡Ã‚ ´4à ¯Ã¢â‚¬Å¡Ã‚ ´4 supercell including 128 atoms. The binding, vacancy formation and migration energies were calculated with 300eV plane-wave cutoff and 12à ¯Ã¢â‚¬Å¡Ã‚ ´12à ¯Ã¢â‚¬Å¡Ã‚ ´12 k-point meshes. The residual atomic forces in the relaxed configurations were lower than 0.01eV/Ã…. The transition states with the saddle point along the minimum energy diffusion path for vacancy migration were determined using nudged elastic band (NEB) method [24] as implemented in VASP. We adopt the harmonic approximation (HA) to consider the contribution of normal phonon frequencies to free energy. The normal phonon frequencies were calcu lated using the direct force-constant approach as implemented in the Alloy Theoretic Automated Toolkit (ATAT) [25] package. Similar cutoff energy, k-point mesh size and supercell size used for the total energies were used for the vibrational calculations. 3. Result and discussion Table 1 illustrates our calculated energies for vacancy formation, migration and binding, as well as the constant ÃŽÂ ± for solute species, the associated paramagnetic activation energies and fully ordered ferromagnetic activation energies for both self- and solute-diffusion. For pure bcc Fe, the vacancy formation energy and migration energy obtained here are consistent with the reported range of values, ΆHf=2.16-2.23 eV and ΆHmig=0.55-0.64 eV [11,26,27]. For Y impurity in bcc Fe, the calculated vacancy binding energy in full ordered ferromagnetic state also compare well with the previous first principles work [28], in which ΆHb=-0.73 eV. It can be seen that Y and La have smaller activation energy than that for Fe self-diffusion, while Ce is predicted to have a lager value of activation energy than that for Fe self-diffusion, in both the ordered ferromagnetic and paramagnetic state. Table 1 Vacancy formation energy ΆHf , solute-vacancy binding energy ΆHb, migration energy ΆHmig, the ferromagnetic activation energy and the paramagnetic activation energy QP; the variable dependence parameter of activation energy on magnetization ÃŽÂ ±. Fe Y La Ce ΆHf(eV) 2.31 à ¢Ã¢â€š ¬Ã¢â‚¬â„¢ à ¢Ã¢â€š ¬Ã¢â‚¬â„¢ à ¢Ã¢â€š ¬Ã¢â‚¬â„¢ ΆHb (eV) à ¢Ã¢â€š ¬Ã¢â‚¬â„¢ -0.69 -0.66 -0.43 ΆHmig (eV) 0.54 0.09 0.17 1.09 ÃŽÂ ± 0.156 0.088 0.038 0.125 (eV) 2.85 1.71 1.82 2.97 QP (eV) 2.47 1.57 1.75 2.64 Solute-vacancy binding energy plays a crucial role in understanding solute diffusion kinetics. Table 2 presents the binding energies of Y, La and Ce atoms with vacancy in their 1nn, 2nn and 3nn coordinate shells. From Table 2 it can be seen that referring to the first nearest-neighbor solute-vacancy pairs, the binding energies are all negative, which implies the solute-vacancy pairs are favorable. Specifically, Y and La impurities are computed to have higher values of solute-vacancy binding energies -0.69 eV and -0.66 eV in 1nn configuration, respectively, while that for Ce is -0.43 eV. Correspondingly, we found that Y, La and Ce atoms relax towards the 1nn vacancy by 22.3%, 19.6% and 12.2% of the initial 1nn distance (2.488 Ã…) after the structure optimization. The interactions of the solute-vacancy pair at the 2nn shells tend to be smaller in magnitude than that of 1nn, and that of Ce-vacancy predicted to be repulsive. The interactions of the 3nn solute-vacancy are relatively we ak, indicating that the interactions of the solute-vacancy are local. According to Le Clair model [13], in the situation that the interactions of the first and second nearest solute-vacancy neighbors are appreciable, the nine different jump frequencies should be considered. To obtain information on the origin of these attractive behaviors, we decompose the total binding energy into the distortion binding energyand the electronic binding energy as [29] . The distortion binding energy can be obtained by the distortion reducing of the bcc Fe matrix when a solute atom and a vacancy combine to form a solute-vacancy pair, and can be expressed as: (5) where and can be calculated as follows: after the supercell containing a solute-vacancy pair (or a substitutional atom) has been fully relaxed, the solute-vacancy pair (or the substitutional atom) is removed from the system, then the total energy can be calculated. denotes the total energy of the pure bcc Fe supercell, and denotes the total energy of the supercell containing a vacancy. Then can be calculated from . The calculated solute-vacancy binding energies of 1nn, 2nn and 3nn are shown in Table 2, along with the energy decomposition for 1nn solute-vacancy binding. The distortion energies (-0.31 to -0.65 eV) for all solute elements(Y, La and Ce) are negative, and much bigger than their corresponding electronic binding energies (-0.04 to -0.12 eV). This implies that the distortion energy accounts for a major part of the total solute-vacancy binding energy, i.e. the strain relief effect contributes significantly to the interaction between the impurity atom and the vacancy, esp ecially for the solute Y and La, which accounted for 94.2% and 97.0% of the total binding energy, respectively. Furthermore, there is a strong correlation between the binding energy and the distance of the solute-vacancy, and the lattice relaxation around the vacancy is local. For the case of Ce-vacancy , specifically, we found that Ce atom relax away from the 2nn vacancy by 4.3% of the initial 2nn distance, which leads to the positive binding energy. Table 2 Decomposition of the total solute-vacancy binding energy into distortion binding energy and electronic binding energy. Units are eV. Solute element Y La Ce ΆHb (1nn) -0.69 -0.66 -0.43 (1nn) -0.65 -0.64 -0.31 (1nn) -0.04 -0.02 -0.12 ΆHb (2nn) -0.16 -0.21 0.10 ΆHb (3nn) -0.06 0.09 -0.05 The calculated migration energies of the different vacancy jumps corresponding to the paths in Fig. 1 are listed in Table 3. The migration energies of w2 jump for Y and La are lower than that of w0 jump for host Fe atom (0.54 eV), while the migration barrier of Ce in bcc Fe is higher than that of Fe self-diffusion. The migration barrier of w2 jump for Y is 0.09 eV, comparable to the reported value of 0.03 eV and 0.02 eV [9, 30]. The results indicate that there is a correlation between the binding energy of solute-vacancy and the migration energy, i.e. the strong attraction of solute-vacancy in 1nn configuration gives rise the low migration energy of the corresponding vacancy jump. For the three solute atoms, because of the strong attraction of 1nn solute-vacancy, the migration barriers of which the 1nn vacancy jump away from the solute atom, i.e. w3, w3, and w3, are higher than that of the opposite jumps, i.e. w4, w4, and w4, as well as that of Fe self-diffusion in pure bcc Fe. And t he same tendency can be found in the results of jump w5 and w6. Table 3 Migration energies for different jumps in the presence of Y, La and Ce in bcc Fe matrix. Units are eV. Jump Y La Ce w2 0.09 0.17 1.08 w3 1.81 1.84 1.55 w4 0.91 0.99 0.92 w3 0.93 1.23 1.07 w4 0.04 0.03 0.08 w3 0.86 0.92 0.87 w4 0.12 0.05 0.11 w5 0.94 0.98 0.89 w6 0.69 0.67 0.82 The correlation factor f2 is related to the probability of the reverse jump of a solute atom to its previous position [31]. Table 4 lists the calculated values of correlation factors for Y, La and Ce at representative temperatures of 850, 1000 and 1150K. The correlation factor of Y is 3.3ÃÆ'-10-5 at 1000K, close to the value of 1ÃÆ'-106 obtained by Murali [9]. For the three elements, the correlation factors of Ce have the highest values, and the correlation factors of La are one order of magnitude lower than that of Y. Therefore, Ce atom is the most difficult to return back to its original position in the temperature range of our investigation. Including the smallest binding energy, highest migration energy and correlation factor, provides an explanation for the low diffusivity of Ce atom. Table 4 Correlation factors (f2) for Y, La and Ce solute-diffusion at representative temperatures of 850, 1000 and 1150K. T(K) Y La Ce f2 f2/ f0 f2 f2/ f0 f2 f2/ f0 850 6.4ÃÆ'-106 1.111 2.9ÃÆ'-107 1.264 0.379 1.373 1000 3.3ÃÆ'-10-5 1.070 2.4ÃÆ'-106 1.223 0.381 1.370 1150 1.2ÃÆ'-104 1.034 1.4ÃÆ'-10-5 1.188 0.383 1.367 Table 5 lists the calculated diffusion activation energies and pre-factors for Fe self-diffusion and Y, La and Ce impurity diffusion. For pure bcc Fe, we find our calculated results are in good agreement with the published values. For Y impurity in bcc Fe, the calculated activation energy in full ordered ferromagnetic state is lower than the previous first principles work, and the pre-factor is as much as two orders of magnitude lager than the reported value. The experimental or calculated diffusion coefficients of La and Ce are not available to the best of our knowledge. For the case of experimental investigation, due to the very small solubilities of La and Ce in iron, the measured data may be affected by segregation of solutes, grain boundary, other impurities and the method of detection. Besides, the theory calculations, e.g. molecular dynamics (MD), first-principles etc. have not been applied widely in the study of RE contained steel yet, so the fundamental data of RE elements i n iron, such as the potential functions of Fe-La and Fe-Ce, is lacking. Table 5 Activation energies in the fully ordered ferromagnetic state () and paramagnetic state (QP), along with diffusion pre-factors for Fe self-diffusion and impurity diffusion of Y, La and Ce in bcc Fe. Reference (kJ mol-1) QP(kJ mol-1) D0(m2/s) Fe Present work 275.3 238.1 2.99ÃÆ'-10-5 Huang et al. [11] 277 239 6.7ÃÆ'-10-5 Nitta et al. [32] 289.7 ±5.1 250.6 ±3.8 2.76ÃÆ'-10-4 Seeger[33] 280.7 242.8 6.0ÃÆ'-10-4 Y Present work 165.9 159.9 1.09ÃÆ'-109 Murali et al. [9] 218.1 à ¢Ã¢â€š ¬Ã¢â‚¬â„¢ 8.0ÃÆ'-107 La Present work 175.6 169.2 2.88ÃÆ'-1010 Ce Present work 286.3 275.8 7.66ÃÆ'-106 Fig. 2 presents a direct comparison between the calculated and published temperature dependent diffusion coefficients for Fe self-diffusion and Y solute diffusion. For Fe self-diffusion, the calculated values are in good agreement with Huang et al. [11] and Nitta et al. [29], but smaller than the measured d

The Life and Accomplishments of Sir Francis Drake Essay -- World Histo

The Life and Accomplishments of Sir Francis Drake The British Empire was a World dominant force throughout the 17th, 18th, and 19th century, but if it wasn’t for the naval defeat of the Spanish Armada in 1588, the British might have never settled what would be the United States. And the person we have to thank is none other than Sir Francis Drake, a common man whose rise from a small country town, to the mighty dragon that the Spanish feared, was the most brilliant Captain during the Elizabethan Era. Sir Francis Drake’s privateering in the Caribbean and the Pacific were the staging grounds for the destruction of the Spanish Armada and the Rise of the British Empire. It was in the Caribbean where Drake inflicted is greatest defeats and captured his greatest prizes. Sir Francis Drake was just the man the British needed to destroy a dominating Spanish monarchy. The Queen however was embarrassed half of the time for Drake’s ability to take basic orders and expand on them to greater serve himself and his country. Although this jeopardized the safety of the Queen by provoking the Spanish into war. Sir Francis Drake was a man who was feared by all countries who sailed under the Roman Catholic Church’s flag. He was hated by some for his piracy and rude, abrupt behavior. He was not a gentleman by British standards, but he was a fair and generous Captain known to let his captured prisoners go free. In some cases even the captured crew and their ships would be let go. He is not totally a just man, he was known to buy favors, and in one case even killed a man because of their disagreement in the Pacific Ocean. But by most people he was a man admired for his clever seamanship and treatment of his fellow sailors. And most of all, he w... ...owerful nation during the 17th, 18th, and 19th century. There’s no doubt that he was the Captain of his own ship and leader of many to follow even after his death in 1596. He would be admired for centuries for his leadership and brilliant privateering maneuvers. His leadership help catapult a nation into the status of world dominant power as well as dominant sea power for centuries to come. Sir Francis Drake, England’s father of the sea, all because of one man’s hatred for a religion and the love of wealth and fame. Work Cited John Hampden, Francis Drake: Privateer; University of Alabama Press, 1972. James A. Williamson, Age of Drake ; Adam & Charles Black, London, 1965. T. W. E. Roche, The Golden Hind ; Praeger Publishers, New York, 1973. Norman J. W. Thrower, Sir Francis Drake and the Famous Voyage ; University of California Press, Berkeley, 1984.

Essay on Eating Disorder - Dying to Be Thin :: Argumentative Persuasive Topics

Dying to Be Thin Seeing an empty box of over-the-counter diet pills in the bathroom at school a couple of weeks ago really got me thinking: what is the ideal body image that we throw at teenagers today? More and more we see people equate success and popularity with beauty and, especially, with being thin. The media, one of the biggest influences on young people, is crammed with images of "the perfect body," and American life seems to revolve around health clubs, diet pills, and fat-free foods. As contributing factors to eating disorders continue to rise in everyday life, so do the statistics. Fifteen percent of the teenagers diagnosed with Anorexia Nervosa will die this year, and as many as 1 in 5 college students are engaging in some form of bulimic behavior. Anorexia is found chiefly in adolescents, especially young women, and female anorexics outnumber males 15 to 1. With numbers this high, someone you know, literally, may be dying to be thin. In medicine, Anorexia Nervosa is a condition characterized by an intense fear of weight gain or becoming obese, as well as a distorted body image. An anorexic will claim to "feel fat" even when emaciated, and will refuse to maintain a normal, minimal body weight. Visible signs of Anorexia include: * fear of food and situations where food may be present; * rigid exercise regimes; * dressing in layers to hide weight loss; * use of laxatives, enemas or diuretics to get rid of food. Treatment techniques for Anorexia include family therapy, group therapy, support or self-help groups, and individual psychotherapy. Given the proper treatment, approximately 50% of diagnosed anorexics will recover completely within 2 to 5 years. Bulimia, characterized by compulsive binge-eating and purging, is very closely related to Anorexia Nervosa. Victims of these two disorders may share many of the same behaviors and concerns, especially the intense fear of becoming fat. For bulimics, food becomes an obsession and an addiction. Some visible signs include: * strict dieting followed by eating binges; * disappearing after a meal; * excessive concerns about weight; * expressing guilt or shame about eating.

Deborah Tannen Analysis Essay

Ap English Tannen Essay Section 1: Theory You Just Don’t Understand Women and Men in Conversation by Deborah Tannen is basically an explanation on how women and men converse. Tannens main goal is to give advice to the different genders in order for them to avoid as much conflict as possible. Tannen’s main ideas are to explain how differently women and men react to each other’s way of being. It’s like they’re in their own little world while living in the same big world. Men tend to try to dominate situations and tend to always want to be at the top.Women do not tend to want to get into conflict but tend to show understanding. These big differences bring them into conflict. A Tannen explains, â€Å"What he wanted conflicted with what she wanted†. (40) Women and men are constantly clashing in opinions. Men are usually trying to be above each other which is something Tannen calls â€Å"one-up†. It is like men are always in competition with people around them. For example, in chapter 2, Tannen explains why men don’t ask for directions. She explains, â€Å"The fact that you have the information, and the person you are speaking to doesn’t, sends a metamessage of superiority.If reasons are inherently hierarchal, then the one who has more information is framed as higher up on the ladder, by virtue of being more knowledgeable and competent. † This shows how men are always trying to be at the top of every conversation. They want to know everything, in order to be at the top of everyone. Women have a completely different view point then men. They aim to be accepted by others, they try to avoid conflict, and they tend to show that they understand what the other person is trying to say.For example, in chapter 6, Tannen begins to explain how in a comic, the two boys are fighting while a girl named Debbie is trying to be the peacemaker. She claims that she is looking for someone but the boys say that the per son isn’t there. Even though she knows the person is there, she acts like she doesn’t know anything to avoid conflict. Tannen explains, â€Å"Females play the role of being peace makers. †(162) This shows how women basically try to avoid any conflict with anyone. Section 2: Setting The setting of the conversation is at lunch in a restaurant for a reunion.There are three women: Cathy and Jeanne are sisters and Mary is their mom. The conversation is taking place at a restaurant called The Cheese Cake Factory at around 12:45. The women are having lunch because Cathy came down to visit them from Venezuela. The women haven’t seen each other in two months. They basically discuss their life styles and explain how their children act. Section 3: Analysis In this conversation, there are no men. Since there are only women, there is no conflict and they basically agree with each other in everything.They talk about their children’s behaviors and no one speaks m ore than one another. However, even though Mary does talk, she speaks less than her daughters do. The women only interrupt each other twice in the entire conversation but it is to add positive feedback to each of their issues. For example, Jeanne interrupts Cathy to say â€Å"of course†, when Cathy is talking about her conditions in Venezuela. Throughout the conversation, the topic basically stays the same. Unlike men, these women don’t try to be â€Å"one-up† from each other in anyway. No one brags about anything and they don’t try to put each other down.In fact, they agree with each other when they share different anecdotes. For example, Jeanne agrees with Mary when Mary says that it was hard to have 3 teenagers at once. Jeanne specifically says, â€Å"How the heck did you do that! † I think Tannens theory of women is proven by this conversation. Since there are just women, they each agree with each other and are very understanding of their conce rns and opinions. Section 4: Reflection In this conversation, I completely agree with what Tannen would think of this conversation. Women always tend to agree with each other and then add feedback to the conversation.Also, men like to be straight to the point while women like to be detailed and concerned. This is exactly what the ladies are doing in this conversation. They do not try to be better than each other in any way; they are simply having lunch. No one tries to take the lead role of the conversation and neither one of them tries to act like they’re better than another. This book has opened my eyes to many things I never noticed. I never noticed why men and women clash so much with each other. Men and women are very different. For example, this book made me feel the need to analyze my parent’s relationship.They do fight because they have different views on how to deal with things. My mom seems to overreact to things in my dad’s eyes. However, my mom feels that my dad doesn’t care so much about her since he feels this way. I agree with her when she compares the genders. However, at times I felt that she would exaggerate. As a woman, I notice that I do many of the things she says in her book. I’m never looking for conflict and I don’t like to brag to people that I don’t really know because it seems like they’ll judge me. However, in this book, I feel that women look weak in her eyes.She feels that they are always willing to avoid conflict but this is not always the case. Women fight as well for what they want. At times, I felt her book had been inaccurate because the ideas were more stuck in the past. For example, the newspaper example in chapter 3. When I read this example, the first think I thought about was my grandparents. They always fight due to the idea of my grandpa always reading the paper rather than talking to my grandma. A lot of couples, nowadays, don’t have this problem. This to me shows that it’s inaccurate information.