Aiming point guidance law for air-to-air missiles

A new aiming point guidance (APG) law is presented which generates a missile turn rate command proportional to the heading error, that is defined as the angle between the current missile heading and predicted aiming point. The target under consideration is assumed to be manoeuvring with constant longitudinal and/or lateral accelerations, and the missile dynamics are modelled as an acceleration-limited first-order lag point mass. The aiming point is calculated based on current intercept geometry and target velocity and position. Time-to-go, a key factor for successful interception, is estimated by a time-to-go predictor. With the heading error defined as stated above, the guidance law can guide the missile into the collision course in the early stage of the engagement. As a consequence, the later part of the missile trajectory tends to be a straight line, provided that the target maintains its current status. The performance of the proposed APG is evaluated by simulation and is compared with the proportional navigation guidance (PNG) and Kim's prediction guidance (PRG) law (Kim 1985). Numerical simulations show that APG is superior to PNG and PRG in both intercept time and miss distance     

Egg White Lysozyme Purification by Ultrafiltration and Affinity Chromatography

Isolation and purification of lysozyme from hen egg white was studied using a two-step procedure. The egg white was diluted 5- to 9-fold with sodium phosphate buffer, and then processed by sequential dilution diafiltration using a UF membrane (molecular weight cut-off 300,000 dalton). The membrane process increased the specific activity of lysozyme 6-fold, and recovered 96% of lysozyme activity. The permeate from diafiltration was further purified by affinity chromatography using chitin as adsorbent. The second step of the process yielded a product of specific activity of 70,400 units/mg protein. The overall lysozyme recovery was 79%.     

利用Sn-Ag-Ti活性焊料直接活化软焊接合Al_(0.3)CrFe _(1.5)MnNi_(0.5)高熵合金与6061铝合金（英文）

高熵合金Al_(0.3)Cr Fe_(1.5)Mn Ni_(0.5)(HEA)具有许多特殊性能。在大气环境、接合温度为250℃保持60 s的条件下,以Sn3.5Ag4Ti为活性焊料对HEA/HEA及HEA/6061-Al进行直接活性软焊接合,并对其进行显微组织及剪力强度分析。实验结果显示,在接合过程中,高熵合金中所有元素缓慢扩散进入连接区域。HEA/HEA和HEA/6061-Al样品的剪切强度分别为(14.20±1.63)和(15.70±1.35)MPa。HEA/6061-Al样品的断裂面呈显明显的半脆性断裂特征。     

珐琅色釉——对现代时尚珠宝首饰的省思

珐琅呈现出丰富多彩和水晶般的质感,给予现代时尚珠宝设计师很大创作空间及独特魅力。在台湾,珐琅产业的发展及技术水准存在不足之处。文章以材料分析方法为基础成功地研发一种新无毒、无铅、高显色和多彩的珐琅色釉,并应用到时尚珠宝饰品。此新型珐琅色釉应用于时尚珠宝首饰的制作,不仅能提高时尚珠宝首饰的技法,更能丰富时尚珠宝首饰质感,增化我国珠宝首饰的市场竞争力。     

Effects of Electrical Stimulation, Hot-Boning and Mixing vs Tumbling on the Physical and Chemical Properties of Beef Logs

Paired sides of 20 steer carcasses were used to determine the effects of electrical stimulation (ES), hot-boning (HB), and mixing vs tumbling on the physical and chemical properties of restructured beef logs. Proximate analysis data showed HB to increase water-holding capacity and ash content over cold-boning (CB). Electrical stimulation increased peak force (PF) values over nonstimulation (NS), but there was no difference in the distance to peak force (DPF) values or energy values, indicating a slight improvement in binding ability with ES. Electrical simulation and HB increased binding ability of the meat proteins. Results of this study suggest that tumbling should be used with HB and mixing should be used with CB to reduce moisture losses.     

Using a functional integration matrix to solve time-varying bilinear systems

The Fourier series approximation approach is employed to analyse time-varying bilinear systems. The functional integration matrix and coefficient matrix of the Fourier series are derived first. The functional integration matrix is used to fulfill the integration process and transform the initial condition to the matrix equation. The product of two truncated functions is replaced by a concise form through the coefficient matrix. The numerical model is derived from the original differential equation based on matrix algebra. An example is illustrated to show the usage of this study, and the results are compared with traditional Fourier series approach and Runge-Kutta method.     

Linear optimal control systems using reduced-order observers via polynomial series

A reduced-order compensatory observer should be appropriately set up to fill the gap between states and observed outputs. In this paper, we use seven polynomial series to approach the reduced-order observer problem. An illustrative numerical example is interpreted to support this technique.     

Study of Ardmore,Oklahoma, storm clouds. I. Convective storm cloud initiation and development based on the remote sensing gravity-wave-induced convection

Abstract

Convective instability can be induced by unstable vertical temperature profiles and can be supported by the release of latent heat of water vapour provided by a large quantity of moisture in the air. It can also be released by the presence of gravity waves. Large amplitude gravity waves have been linked to the onset of convective storm systems. In this study, the vertical velocity of convection initiated by gravity waves was investigated. The study of Ardmore, Oklahoma, storms showed that weak convection was initiated by gravity waves having wave periods of 35 min and the convection was enhanced by gravity waves having wave periods of 20 min. Evidence for cloud formation, due to the condensation of water vapour through convection initiated by the gravity waves, was obtained from rapid-scan satellite imagery and radar summaries. In this particular case, the convective motion, initiated and supported by the gravity-wave-induced activity (excluding contributions made by other mechanisms), reached its maximum value about one hour before the production of the funnel clouds. In this study, we did not rule out the contributions made by other mechanisms, such as low-level convergence and others, toward the initiation of convection; however, our main purpose is to discuss the role of gravity waves in wave-induced convection contributing to the fractions of formation and development of severe convective storms.     

Solution of variational problems using the Fourier series operational matrix

There are many functions having the property of orthogonality. Among them are Walsh functions, block-pulse functions, Chebyshev functions and Legendre functions. Recently, many scholars and researchers made new approaches to solving variational problems via orthogonal functions. This paper suggests a more simple and powerful orthogonal method—the Fourier series operational matrix for integration—which is derived and used to solve a variational problem.