A universal matrix solver for integral-equation-based problems

A new method has been developed for compressing the matrices that occur in most integral-equation-based computer programs. This method is easy to interface with existing computer programs, and allows them to run significantly faster and with significantly less memory. This method applies not only to electromagnetic and acoustic computation, but also to most programs involving a Green's function or any integral equation with a kernel having some smoothness properties. Our numerical computations, running on a high-end personal computer, have achieved compression ratios of fifty times, and compressed inversion of the matrices fifty times faster than by previous methods. For larger problems, solved on high-performance computers, these ratios would improve to about one thousand to one for larger moment method problems.     

A simple impulsiveness correction factor for control of electromagnetic interference in dynamic wireless applications

The emerging software defined radio technologies will be an enabler for a new generation of dynamic wireless systems. It will also open up the possibility of allocating frequencies in a, more dynamic way than today. From an intersystem-interference point of view, this can cause unforeseen problems to occur due to the increased complexity in such applications. In such applications, a measure indicating whether or not a frequency band is possible to use from an electromagnetic interference point of view, must be found. A simple approach is to use the measured total average interference power within the receiver band. Since the interference impact on modern digital communication systems from an interference signal does not only depend on the power but also on the actual waveform of the interference signal, some kind of quality measure of the average-power approach would be convenient to use. In this paper, we introduce a simple quality measure of the average-power approach so that a rough adjustment for the interference-waveform properties can be done.     

An adaptive p-persistent MAC scheme for multimedia WLAN

The letter proposes an adaptive p-persistent-based (APP) medium access control (MAC) scheme for the IEEE 802.11e distributed WLAN supporting multimedia services. The APP MAC scheme adaptively gives differentiated permission probabilities to transmission stations which are in different access category and with various waiting delay. Simulation results show that the APP MAC scheme can improve the performance of multimedia WLAN, such as small voice packet dropping probability, low delay variation, and high system throughput, compared to conventional MAC algorithms     

Bandpass filters with reconfigurable transmission zeros using varactor-tuned tapped stubs

In this letter, bandpass filters with one or two tunable transmission zeros are proposed. The reconfigurable transmission zeros are implemented through varactors in combination with tapped quarter-wavelength stubs. Based on mixed mode simulations including EM simulation and circuit simulation, the proposed filters were designed and fabricated on low-cost FR4 board. The measurement results verified the design concepts.     

The colored revolution of bioimaging

This paper provides an overview of the main aspects of modern fluorescence microscopy. It covers the principles of fluorescence and highlights the key discoveries in the history of fluorescence microscopy. The paper also discusses the optics of fluorescence microscopes and examines the various types of detectors. It also discusses the signal and image processing challenges in fluorescence microscopy and highlights some of the present developments and future trends in the field.     

Self-oscillating dimmable electronic ballast

This paper presents a simple alternative for an electronic ballast operating in self-sustained oscillating mode with dimming capability for fluorescent lamps. A simple modification in one of the gate drivers side circuit allows the lamp to dim without compromising the simplicity, reliability, and low cost which characterize the self-oscillating electronic ballast (SOEB). A qualitative analysis is presented to explain the behavior of the proposed self-oscillating electronic ballast with dimming feature. In addition, the stability and the key equations for the design are derived using the extended Nyquist criterion and describing function method. Experimental results from two 40-W electronic ballasts are presented to demonstrate the performance and to validate the analysis carried out.     

浅谈自育亲本在甘蔗杂交育种中的作用

统计分析了国内外主要育成品种及亲系，发现用自育品种和材料作为杂交亲本育成的品种在统计品种数中占有相当大的比例。台湾占85．7％、四川50．0％、江西42．9％、广东37．5％、云南占了27％、广西16．7％、福建6．7％。印度、美国、巴巴多斯、毛里求斯分别是100％、95．5％、92．9％和100％。说明使用自育品种和材料作为亲本在甘蔗杂交育种中有相当重要的作用。     

Transient response of ARROW VCSELs under external optical feedback

The effect of external optical feedback on the transient response of antiresonant reflecting optical waveguide (ARROW) vertical-cavity surface-emitting lasers (VCSELs) is studied. It can be shown that the proper design of ARROW can suppress the excitation of high-order transverse leaky mode as well as increase the critical feedback strength so that stable high-power single-mode operation of VCSELs can be obtained even under the influence of strong external optical feedback.     

Estimation and Optimization of the Principal H-Maser Parameters

The scale along the coordinate axes in the equations of motion hitherto used for an H-maser (in relative units) is shown to depend on Q as the quality factor for an H-maser. This hinders both analysis of the operation of the H-maser and optimization of its parameters. The modified equations of motion proposed here do not have that shortcoming. We determine the atomic flux into the bulb that gives the H-maser the best metrological characteristics.