Typical comparisons between plasma bubble and blob distributions at different altitudes over the Indian sector using a unique combination of satellite-based observations – a case study

We report in this article, for the first time, on the altitudinal variations of ionospheric irregularities during post-sunset hours between 14 and 17 October 2001 at Indian longitudes by using a unique combination of Challenging Mini Satellite Payload (CHAMP), Republic of China Satellite (ROCSAT-1), and Defense Meteorological Satellite Programme (DMSP) satellites located at about 400, 650, and 850 km, respectively. It became possible for us to study the width of plasma bubbles and plasma blobs in the longitudinal (zonal) direction at different altitudes along with temporal variations of ion velocity components in horizontal (V_y) and vertical (V_z) directions as probed by ROCSAT-1 and DMSP satellites. The dominant features noticed in V_y and V_z components are their anti-correlation relationship at the ROCSAT-1 satellite’s altitude (mirroring effect). The most important observation from this study is that plasma bubbles are found to have occurred immediately after post-sunset hours, whereas plasma blobs were observed after three hours following the bubbles’ appearance time and continued until pre-sunrise hours at higher altitudes between around ±5° and ±20° from the magnetic equator, which indicate that the plasma blobs emanate from plasma bubbles that generated at the bottomside of the ionospheric F-layer shortly after sunset on similar lines to a few recent research studies. It is therefore believed that the polarized electric fields generated inside plasma bubbles might have played a role in the generation of higher-altitude plasma blobs. Importantly, the calculated power spectra of bubbles and blobs show a nearly equal trend, indicating that they are intricately connected with each other.     

Gas�Cliquid flow stability and bubble formation in non-Newtonian fluids in microfluidic flow-focusing devices

This communication describes the gas–liquid two-phase flow patterns and the formation of bubbles in non-Newtonian fluids in microfluidic flow-focusing devices. Experiments were conducted in two different polymethyl methacrylate (PMMA) square microchannels of, respectively, 600 × 600 and 400 × 400 μm. N₂ bubbles were generated in non-Newtonian polyacrylamide (PAAm) solutions of different concentrations. Slug bubble, missile bubble, annular and intermittent flow patterns were observed at the cross-junction by varying gas and liquid flow rates. Gas and liquid flow rates, concentration of PAAm solutions, and channel size were varied to investigate their effect on the mechanism of bubble formation. The bubble size was proportional to the ratio of gas/liquid flow rate for slug bubbles and could be scaled with the ratio of gas/liquid flow rate as a power–law relationship for missile bubbles under wide experimental conditions.     

令人困惑的a=*a

“指向二维数组的指针和指针变量”是C语言程序设计中的难点,对于初学者来说有些概念难以理解,容易产生混淆;在实际编程时,也容易错误地加以应用。本人在教学实践中经过摸索发现,从容易理解的一维数组出发,循序渐进地学习与理解此部分内容,就会收到良好的学习效果。     

Optimizing a damped system – a case study

We consider a second-order damped-vibrational system described by the equation M ?+C(v) [xdot]+K x=0, where M, C(v), K are real, symmetric matrices of order n. We assume that the undamped eigenfrequencies (eigenvalues of (λ² M+K) x=0) ω₁, ω₂, …, ω _n , are multiple in the sense that ω₁=ω₂, ω₃=ω₄, …, ω _n?1=ω _n , or are given in close pairs ω₁ ≈ ω₂, ω₃ ≈ ω₄, …, ω _n?1 ≈ ω _n . We present a formula which gives the solution of the corresponding phase space Lyapunov equation, which then allows us to calculate the first and second derivatives of the trace of the solution, with no extra cost. It can serve for the efficient trace minimization.     

Is a Semantic Web Agent a Knowledge-Savvy Agent?

The issue of knowledge sharing has permeated the field of distributed AI and, in particular, its successor, multiagent systems. Through the years, many research and engineering efforts have tackled the problem of encoding and sharing knowledge without the need for a single, centralized knowledge base. The proposed solutions to this problem are based, more or less, on stringent assumptions, such as static, shared ontological models, or the existence of a common blackboard (or "Linda Space") environment where entities can share knowledge. However, the uptake of the World Wide Web and the emergence of modern computing paradigms, such as distributed, open systems, have highlighted the importance of sharing distributed and heterogeneous knowledge on a larger scale-possibly on the scale of the Internet.     

Implementing a feasibility study “a procedural approach”

The aim of the paper is to present a procedural approach for implementing a feasibility study. It consists of three chapters.The first is concerned with General Aspects and Proposals, and covers: the meaning and objectives of the feasibility study, the relations between long range planning and feasibility studies, proposals for initiating and conducting the feasibility study, and suggestions for using “prototyping” during the feasibility study.The second proposes a Feasibility Study Methodology, and finally The third gives the “format” for Presenting a Feasibility Study to Management.     

Implementing a Serializer Using a Java XML Schema API

W3C XML （Extensible Markup Language） Schema defines a set of abstract components, which carry the core semantics of document structure definition. There has been no standard API for accessing these components or their structures yet. The MARKUP Technology Company has specified a Java API for accessing XML Schema and submitted it to the W3C as a possible basis for standard Schema API. An overview of the schema API is provided and then XML schema serializer is implemented using this API in this paper.     

Assigning a kekulé structure to a conjugated molecule

The Edmonds Matching Algorithm, which leads easily to finding a perfect matching in a chemical graph, which is equivalent to a Kekulé structure in a conjugated molecule, is recalled. An extension is made to the case where only vertices of a specified set must be covered by edges of the matching which is sought.     

走进802.11a

在现在的工作(家庭)环境中,您是否感觉需要无线设备给我们提供更加便捷的网络连接了么?以往当我们提起网络连接设备,通常人们所想到的是网卡、集线器、交换机以及各种网络线缆。从     

Velocity planning for a mobile robot to track a moving target — a potential field approach

Potential field method has been widely used for mobile robot path planning, but mostly in a static environment where the target and the obstacles are stationary. The path planning result is normally the direction of the robot motion. In this paper, the potential field method is applied for both path and speed planning, or the velocity planning, for a mobile robot in a dynamic environment where the target and the obstacles are moving. The robot’s planned velocity is determined by relative velocities as well as relative positions among robot, obstacles and targets. The implementation factors such as maximum linear and angular speed of the robot are also considered. The proposed approach guarantees that the robot tracks the moving target while avoiding moving obstacles. Simulation studies are provided to verify the effectiveness of the proposed approach.     

Cobol: a historic past, a vital future?

One of the strangest stories in the software world centers around the programming language Cobol. Academics have reviled it for decades; its demise has been predicted since the 1960s; industry gurus have suggested that programmers who know only Cobol are committing career suicide. You would think, based on all this bad press, that Cobol was not long for this software world. Yet the giant lumbers on. In poll after poll, it is either the most-used or the second-most-used programming language in industry. In fact, in one industry poll, each year those contacted predict that Cobol's use will diminish by the next poll, and each year the findings are that Cobol is the only language whose use has actually increased. The devil refuses to die. What's with Cobol? I give my Loyal Opposition answer to that question and then give some input on the subject from a Cobol expert who is tracking Cobol's future directions     

Does a back support have a positive biomechanical effect?

Back supports, or lifting belts, are widely used. Subjects, free of low back pain, lifted in a simulated task, meeting the 1993 NIOSH guidelines. The back support reduced the electromyographic signal in the dorsal muscles. The back support also reduced the height loss as measured by a stadiometer. In most subjects the support also gave a subjective impression of increased support and increased lifting capacity.     

H ∞ control of a suspension with a magnetorheological damper

This research work presents an H _∞ controller based on a Takagi–Sugeno (T–S) fuzzy model for a two-degrees-of-freedom (2-DOF) one-quarter-vehicle semi-active suspension with a magnetorheological damper where the actuator dynamics are included in the control synthesis. These dynamics enclose nonlinear damper phenomena, avoided in many other studies, and that can improve the suspension system by means of a more accurate model. The objective is to obtain a semi-active suspension that considerably improves the passive suspension efficiency based on some frequency domain performance criteria. The advantage of having the T–S system as a reference is that each piecewise linear system can be exposed to the well-known control theory. Besides, the proposed solution is compared with the recent reported work to highlight its advantages. A case of study is included and simulation work supports the results. The methodology applied herein can be extended to a half-vehicle model, and to the four wheels to have a global chassis control in order to maximise passenger comfort and vehicle stability.     

File distribution using a peer-to-peer network––a simulation study

As the Internet became widespread, people saw it as a way of distributing content. But while the average bandwidth capacity is increasing, users around the world are trying to share more data. Although the servers are able to acquire more bandwidth, they cannot keep up with the rapidly increasing requests of the users. Several systems appeared that alleviate the server from the dissemination process. But such systems are not always suitable for disseminating highly anticipated files of considerable size. The evolution of peer-to-peer systems gave a new way of attacking this problem. Each user can assist the dissemination process by acting as a server as well. In this paper the way traditional systems meet users' demands is demonstrated, and simulation results of a peer-to-peer approach based on a mobile agent platform are presented. Our focus is on how different parameters can affect the dissemination process of a highly anticipated file in this network.     

Such a Beautiful Disease

奈奈是一家网络游戏公司的小MM。有句话叫做“命悬一线”，像我这样一天超过12个小时面对电脑的人，工作、生活就寄托在那根小小的网线上。     

Approximating a helix segment with a rational Bézier curve

From a differential geometric point of view a helix segment can be considered as a spatial generalization of a circular arc. Thus for problems of shape preservation and geometric modelling an approximate rational representation of a helix segment is of interest. In this paper rational Bézier curves of degree 4, 5 and 6 are presented that approximate a helix segment. The approximants fulfill certain geometric constraints. A generalized degree elevation for rational polynomials in Bézier representation is discussed and used for the construction.     

Building a domain-specific compiler for emerging processors with a reusable approach

High-performance computing and deep learning domains have been motivating the design of domain-specific processors.Although these processors can provide promising computation capability,they are notorious for exotic programming paradigms.To improve programming productivity and fully exploit the performance potential of these processors,domain-specific compilers(DSCs) have been proposed.However,building DSCs for emerging processors requires tremendous engineering efforts because the commonly used...