Effect of methods of demagnetization on the energy required to magnetize steel

In this investigation the first series of tests consisted of obtaining zero flux in two varieties of steel from various maximum flux values and by three different methods. B-H curves were obtained after demagnetization by the three methods and from the maximum value of these B-H curves hysteresis loops were taken.One method of demagnetizing was that suggested by the U. S. Bureau of Standards, which consists of current reversals through a magnetizing winding, in which current values are gradually reduced to zero. The second method consisted of applying a negative current of such an amount that the resultant value of flux would be such that when the current was released the flux value would go to zero. The third method was substantially the same as the second except the zero flux was approached from the direction of opposite polarity.The resultant B-H curves proved to be different from each other and to depend upon not only their origin but the previous history of the material as regards methods of demagnetization.The areas between the curves were evaluated.It was found that in cases of two of the three typical B-H curves the B-log H curves gave straight lines for part of the range involved.A second series of tests consisted of taking a set of hysteresis loops and repeating the determinations, using a greater number of steps to find if by taking a greater number of steps there might be a greater indicated energy loss. The results of this group of tests were not sufficiently definite to warrant conclusions.     

Behavioral innovation: Pilot study and new big data analysis approach in household sector user innovation

Innovation researchers have begun to look beyond how users develop tangible objects or product innovations and moved to investigate the existence and impact of intangible user-developed innovations in techniques and services in the household sector . In this paper, to incorporate technique and service innovations and other varieties of intangible innovations not yet described in the literature into an efficient and encompassing typology, we propose the new concept of intangible Behavioral Innovation as an overarching category that stands in contrast to tangible product innovation. Behavioral innovation is defined as consisting of one or a connected sequence of intangible problem-solving activities that provide a functionally novel benefit to its user developer relative to previous practice. We demonstrate in a pilot study using a relatively novel big data-gathering and semantic analysis approach that behavioral innovation exists and can be identified in user-generated content posted openly online in peer-to-peer discussion forums relating to household sector activities such as parenting. The preponderance (N = 138) of the 168 user innovations captured in our samples of discussion comments were intangible behavioral innovations, most of which were developed by women. The majority of behavioral innovations identified were diffused by their user developers in response to specific requests for help or advice from peers in their online community. Thus, incorporating the new concept of intangible behavioral innovation into studies of user innovation's scope and significance in the household sector can serve to clarify which users innovate in our communities of interest, what and how they innovate, why they are triggered to diffuse their innovations peer-to-peer, and how their innovative activities might impact social welfare.     

Heat transfer in packed bed heat recuperators-II. The film coefficient for dry sorbent solids

An elaborate experimental set up is described that was used to measure the thermal expiration curves of heat recuperators, that had been constructed with guard heaters and vacuum insulation to minimize heat losses. A much more general model is used along with a precision numerical analysis technique to show that a film coefficient correlation of the Dittus-Boelter type did an excellent job of representing the results from 162 runs in which three feed gas temperatures, two flow rates, two particle size ranges, one bed diameter and five desciccants were used. For comparison sake the reported film coefficient correlation is finally assembled in a table along with others found in the literature.     

Light-inadequacy of the ultraviolet theory of ionization in the E-layer

From the reports of the CRPL, average yearly values of h′_E, h′_F1,f °_E and N_F1, for the months of January, March, June, July, September, and December of the years 1944 to 1949 were computed and plotted against the magnetic latitude. Altogether some 25,000 individual records were averaged. Seven curves were plotted. They showed that: (1) all curves are symmetrical with respect to the magnetic equator; (2) the h′_E, h′_F1, f⁰_E and the N_F, curves all swing up and down as the magnetic latitude, north and south, increases; (3) the h′_E is definitely periodic with constant period and constant amplitude; (4) the h′_E curve rises only slightly (on the average) with latitude. These results appear to be inconsistent with the ultraviolet light theory of ionization.     

澜沧江流域潜在蒸散发敏感性分析

蒸散发对气候变量的敏感性研究是近年来水文学的热点之一,对探讨水循环对气候变化的响应具有重要意义。本文利用1960年-2005年澜沧江流域及其周边35个气象站的逐日常规气象观测数据,基于Penman-Monteith公式,计算了1月、7月及年3个不同时间尺度下潜在蒸散发对平均气温、相对湿度、风速及日照时数的敏感系数,分析了澜沧江流域潜在蒸散发对各气候变量的敏感性及其时空变化规律。结果表明各站潜在蒸散发对各变量的敏感系数空间分异明显,流域整体上对日照时数最为敏感。几十年来对日照时数的敏感性在1月主要为增加趋势,7月则为减小趋势。     

Superconductivity in chromium nitrides Pr3Cr10-xN11 with strong electron correlations

Exploration of superconductivity in Cr-based compounds has attracted considerable interest because only a few Cr-based superconductors (CrAs, A₂Cr₃As₃ and ACr₃As₃ (A = K, Rb, Cs, Na)) have been discovered so far and they show an unconventional pairing mechanism. We report the discovery of bulk superconductivity at 5.25 K in chromium nitride in Pr₃Cr_10-xN₁₁ with a cubic lattice structure. A relatively large upper critical field of H_c2(0) ∼ 12.6 T is determined, which is larger than the estimated Pauli-paramagnetic pair-breaking magnetic field. The material has a large electronic specific-heat coefficient of 170 mJ K⁻² mol⁻¹—about 10 times larger than that estimated by the electronic structure calculation, which suggests that correlations between 3d electrons are very strong in Pr₃Cr_10-xN₁₁, and thus quantum fluctuations might be involved. Electronic structure calculations show that the density of states at the Fermi energy are contributed predominantly by Cr 3d electrons, implying that the superconductivity results mainly from the condensation of Cr 3d electrons. Pr₃Cr_10-xN₁₁ represents a rare example of possible unconventional superconductivity emerging in a 3D system with strong electron correlations. Nevertheless, clarification of the specific pairing symmetry needs more investigation.     

Tunable electrochemical pH modulation in a microchannel monitored via the proton-coupled electro-oxidation of hydroquinone

Electrochemistry is a promising tool for microfluidic systems because it is relatively inexpensive, structures are simple to fabricate, and it is straight-forward to interface electronically. While most widely used in microfluidics for chemical detection or as the transduction mechanism for molecular probes, electrochemical methods can also be used to efficiently alter the chemical composition of small (typically <100 nl) microfluidic volumes in a manner that improves or enables subsequent measurements and sample processing steps. Here, solvent (H₂O) electrolysis is performed quantitatively at a microchannel Pt band electrode to increase microchannel pH. The change in microchannel pH is simultaneously tracked at a downstream electrode by monitoring changes in the i-V characteristics of the proton-coupled electro-oxidation of hydroquinone, thus providing real-time measurement of the protonated forms of hydroquinone from which the pH can be determined in a straightforward manner. Relative peak heights for protonated and deprotonated hydroquinone forms are in good agreement with expected pH changes by measured electrolysis rates, demonstrating that solvent electrolysis can be used to provide tunable, quantitative pH control within a microchannel.     

Optimal circularly symmetric quantizers

Polar coordinates quantization of the bivariate Gaussian and other cir- cularly symmetric sources has already been investigated. The schemes quantize the polar coordinates representation of the random variables independently in an attempt to reduce the mean square error below that of an analogous rectangular coordinates quantizer. It has been shown for the Gaussian case that the polar quantizer outperforms the rectangular quantizer when the number of levels N is large, while for small N, the rectangular form is often better than the polar form. This paper is an investigation of the optimality of polar quantizers with the subsequent development of optimal circularly symmetric quantizers (labelled Dirichlet polar quantizers).     

A principal stress method of stress analysis

The equations of equilibrium in a stress field as given by Lamé are compared with those given by Cauchy. The (P ? Q and P ? R) terms of the Lamé equations identified by the new words detend and double detend are invariant for any point in a stress field. The principal stresses are defined as real stress components. The $\text{?Xx}\text{?x}$ terms of the Cauchy equations are considered as imaginary force components. Real and imaginary stress and force components are differentiated by the differences between ray vectors, as for example a force which has only one real value and direction, and diffuse vectors, as for example a gradient, which has a real value in any direction. Shear is differentiated from detend value by its variation with the direction in which it is taken. Shear is found to be an imaginary component of force parallel to a plane.The photoelastic equidetend (isochromatic) and isoclinic maps of a plane stress field define, for any point, a gradient triangle with the three maximum gradients, Δ(P ? Q) ΔP and Δ ? Q, for its sides. Five quantities, the detend (P ? Q), the ratio of the detend to its gradient (r₄), the ratio (r₃) of the isoclinic normal ds₃ to the stress axis direction change along its length dα, the direction of the equidetend normal (θ) and the orientation of an isoclinic line (ω) with reference to a principal stress direction, determine each gradient triangle. Five equations which define elements of the gradient triangle in terms of the five measurable quantities, are developed. Definition of the triangle can be complete with two of the five measurable quantities or two of the five equations omitted. Graphic integration of principal stress changes along any line in a stress field can be made by plotting the line straight and measuring the area swept out by the normal projections, along the line, of the sides of the gradient triangle, after it has been rotated through 90 degrees.Properties of the gradient triangle are used to solve several symmetrical stress problems and to integrate along two lines through a stress field.     

Closed plane curves described by finite and infinite sums of rotating vectors

A large group of closed plane curves may be classified as roulettes, including epicycloids, hypocycloids, and related epitrochoids and hypotrochoids. The equation for the roulette in complex polar form shows that any roulette may be described by the vector sum of two vectors of specified constant magnitudes rotating with constant angular velocities. Methods for plotting, and for electronic display of roulettes are described. An equation is derived for a roulette approximation for an N-sided regular polygon. In particular, an application to two-dimensional potential theory is described and illustrated by consideration of the roulette approximation for a square as an equipotential curve, with derivation of equations for equipotential curves in the field surrounding the square. General equations are derived for given closed plane curves with points whose x and y coordinates may separately be expanded in Fourier series as functions of the polar angle, assuming these expansions are valid. It is shown that, in general, a closed plane curve may be considered as being described by an infinite sum of vectors, each rotating in a circle. Simplifying effects of symmetry about a polar axis and/or about the origin are discussed, and methods for harmonic analysis of a given closed plane curve with aid of an electronic calculator are described.     

On Systematic Procedures for Constructing Magic Squares

In the first part of the paper, a systematic procedure for constructing high-order magic squares as an extension of the lower-order basic magic squares is developed and demonstrated. For a 2N x 2N magic square, one can start with a basic N x N magic square, say, N = 3,4,5 or 7,11,13. Using small 2 x 2 squares, like (1,2,3,4) or (5,6,7,8), to fill the elements of the basic N x N magic square according to the ordering of the magic square, one develops the 2N x 2N magic square automatically. For a 3N x 3N magic square, one can choose another basic N x N magic square, say, the 4 x 4 magic square. Then, inserting 3 x 3 small squares in the 16 empty spaces according to the ordering of the 4 x 4 magic square, one develops the 12 x 12 magic square. There may be small adjustments in the numbering of (1,2,3,4) in the 2 x 2 small square, or of (1,2,3,4,5,6,7,8,9) in the 3 x 3 small square to form the proper 2N x 2N or 3N x 3N magic squares. In most cases, the correct results are obtained without adjustments. For N = 4, 4N x 4N produces the 16 x 16 magic square. For N = 5 or 7, using 2 x 2 small squares produces 10 x 10 or 14 x 14 magic squares. Part II of the paper gives a review of other known procedures for constructing odd and even order magic squares with illustrative examples for 4 x 4, 5 x 5, 7 x 7, 10 x 10, 11 x 11, 13 x 13, 15 x 15, 17 x 17, 19 x 19 and 20 x 20 magic squares. One 18 x 18 magic square is given in Part I. In the Appendix, the G and H squares, given by Moschopulus of Constantinople nearly five centuries ago, are discussed concerning symmetrical and pandiagonal squares. It is shown that H can be modified to form H₁ which is both symmetrical and pandiagonal.     

Direct transformation of dinitrogen: synthesis of N-containing organic compounds via N−C bond formation

N-containing organic compounds are of vital importance to lives. Practical synthesis of valuable N-containing organic compounds directly from dinitrogen (N₂), not through ammonia (NH₃), is a holy-grail in chemistry and chemical industry. An essential step for this transformation is the functionalization of the activated N₂ units/ligands to generate N−C bonds. Pioneering works of transition metal-mediated direct conversion of N₂ into organic compounds via N−C bond formation at metal-dinitrogen [N₂-M] complexes have generated diversified coordination modes and laid the foundation of understanding for the N−C bond formation mechanism. This review summarizes those major achievements and is organized by the coordination modes of the [N₂-M] complexes (end-on, side-on, end-on-side-on, etc.) that are involved in the N−C bond formation steps, and each part is arranged in terms of reaction types (N-alkylation, N-acylation, cycloaddition, insertion, etc.) between [N₂-M] complexes and carbon-based substrates. Additionally, earlier works on one-pot synthesis of organic compounds from N₂ via ill-defined intermediates are also briefed. Although almost all of the syntheses of N-containing organic compounds via direct transformation of N₂ so far in the literature are realized in homogeneous stoichiometric thermochemical reaction systems and are discussed here in detail, the sporadically reported syntheses involving photochemical, electrochemical, heterogeneous thermo-catalytic reactions, if any, are also mentioned. This review aims to provide readers with an in-depth understanding of the state-of-the-art and perspectives of future research particularly in direct catalytic and efficient conversion of N₂ into N-containing organic compounds under mild conditions, and to stimulate more research efforts to tackle this long-standing and grand scientific challenge.     

N-step off-line MPC design of nonhomogeneous Markov jump systems: A suboptimal case

This paper mainly concerns N-step off-line suboptimal predictive controller design for discrete nonhomogeneous Markov jump systems, in which the Markov chains are time-varying transition probabilities matrix modeled as a polytope. The design procedure is divided into N-step, more precisely, the first is to design the Nth step when the changes of Euclidean form of mode-dependent feedback law between the Nth and the (N+1)th asymptotically stable mode-dependent ellipsoids are less than the given accuracy. Then the N  th asymptotically stable mode-dependent invariant ellipsoid is defined. In the previous (N−1)$(N-1)$ steps, an off-line mode-dependent predictive controller is designed to drive the state to this small area including the origin. Compared with on-line MPC algorithm, the computation time is dramatically reduced while the dynamic performance of controller is comparable. One numerical example is presented to illustrate the validity of the developed results.     

武威绿洲农业开发对民勤绿洲来水量的影响——基于水足迹的视角

基于历史观测数据统计分析了1956年-2003年石羊河上游天然来水量与下游民勤绿洲来水量变化趋势,采用生产法计算了1950年-2006年武威绿洲农业水足迹,定量揭示了石羊河中游武威绿洲农业开发对区域水资源的真实占用及其对下游民勤绿洲来水量的影响。研究结果表明:①由于石羊河中游武威绿洲人类活动加剧,下游民勤绿洲来水量呈减少趋势;②中游武威绿洲农业水足迹呈快速上升趋势,粮食作物水足迹占最大比重;③中游武威绿洲农业水足迹与下游民勤绿洲来水量呈显著负相关关系,中游农业水足迹每提高1×108m3,下游来水量将减少0.2543×108m3;中游粮食作物水足迹每提高1×108m3,下游来水量将减少0.5021×108m3,中游武威绿洲农业开发是下游民勤绿洲来水量减少的最重要人文活动,粮食作物种植规模的扩大对下游来水量的影响很大;④通过控制农业生产规模,调整农业内部结构,降低单位农产品的虚拟水量,进而控制中游武威绿洲农业水足迹增长趋势是缓解下游民勤绿洲生态恶化的重要手段。     

Analysis of adaptive detection of moderately fluctuating radar targets in target multiplicity environments

In this article, we provide a complete detection analysis, in its exact form, of what is known as moderately fluctuating radar targets when the background environment contains a number of interfering targets along with the target under test. The illumination of this class of radar targets by a coherent pulse train, return a train of correlated pulses with a correlation coefficient in the range 0<ρ<1 (intermediate between SWII and SWI models). Since the adaptive detection is one of the desirable features for modern radar receivers, it becomes of importance to adaptively detect this class of targets. The attractive class of adaptive detectors is that based on order-statistics (OS) technique. The more advanced version of the OS algorithm, known as the generalized trimmed-mean (GTM) scheme, is chosen here to carry out this task. It implements trimmed averaging of a weighted ordered range samples. This processor is analyzed for the case where the radar receiver incorporates a postdetection integrator amongst its contents and where the operating environment is multitarget. The primary and the secondary interfering targets are assumed to be fluctuating in accordance with partially correlated χ² fluctuation model. SWI and SWII well-known models represent the cases where the signal is completely correlated and completely decorrelated, respectively, from pulse to pulse. It is shown that the processor performance improves, for weak SNR of the primary target, as the correlation coefficient ρ_s increases and this occurs either in the absence or in the presence of spurious targets. For strong SNR, on the other hand, the processor performance degrades as ρ_s increases and the SWI and SWII models enclose the correlated target case and this behavior is common for all GTM based schemes.