An integrated equalizer of the gigahertz range based on heterojunction bipolar transistors

The questions of the design of integrated circuits of an equalizer based on heterojunction silicon-germanium transistors are considered. High speed tuned blocks of the equalizers are a features of the device. The computer modeling and experimental studies of the devices for signal transfer at a rate of 12.5 Gbit/s are performed. The experimental results concur well with the results of modeling.     

An efficient electron-beam-pumped semiconductor laser for the green spectral range based on II–VI multilayer nanostructures

Emission characteristics of an electron-beam-pumped Cd(Zn)Se/ZnMgSSe semiconductor laser are studied. The laser’s active region consists of a set of ten equidistant ZnSe quantum wells containing fractional-monolayer CdSe quantum-dot inserts and a waveguide formed by a short-period superlattice with the net thickness of ～0.65 μm. Lasing occurs at room temperature at a wavelength of 542 nm. Pulsed power as high as 12 W per cavity face and an unprecedentedly high efficiency of ～8.5% are attained for the electron-beam energy of 23 keV.     

An integrated system based on wireless sensor networks for patient monitoring,localization and tracking

This works describes the system LAURA which provides patient localization, tracking and monitoring services within nursing institutes through a wireless sensor network. The system is composed of three functional blocks: a localization and tracking engine which performs localization out of samples of the received signal strength and tracking through a particle filter; a personal monitoring module based on bi-axial accelerometers which classifies the movements of the patients eventually detecting hazardous situations, and a wireless communication infrastructure to deliver the information remotely. The paper comments on the design and dimensioning of the building blocks. Two approaches are proposed to the implementation of the localization and tracking engine: a centralized implementation where localization is executed centrally out of information collected locally, and a distributed solution where the localization is performed at the mobile nodes and the outcome is delivered to the central controller. Strengths and weaknesses of the two solutions are highlighted from a system’s perspective in terms of localization accuracy, energy efficiency and traffic loads. LAURA modules are finally tested in a real environment using commercial hardware. The main outcomes are an average localization error lower than 2 m in 80% of the cases and a movements classification accuracy as high as 90%.     

An automated system for the registration and comparison of photographic images in medicine

A system is presented for digitization and automated comparison of photographic images of patients obtained at different times using a high-precision video camera. The images can be acquired either directly or from slides. The two images to be compared are registered using a complex geometrical and gray-level registration model including six parameters (planar, translation, rotation, magnification, linear transformation of the gray levels). The values of the registration parameters are automatically calculated by maximizing an integer similarity measure selected for robustness. The optimization of this function with respect to the registration parameters is performed using an adaptive random search strategy. The analysis of the differences between the registered images can be carried out through visual inspection of the subtraction image in which artifacts due to remaining infrapixel shifts have been suppressed.     

An integrated two-level hierarchical system for decision making in radiation therapy based on fuzzy cognitive maps

The radiation therapy decision-making is a complex process that has to take into consideration a variety of interrelated functions. Many fuzzy factors that must be considered in the calculation of the appropriate dose increase the complexity of the decision-making problem. A novel approach introduces fuzzy cognitive maps (FCMs) as the computational modeling method, which tackles the complexity and allows the analysis and simulation of the clinical radiation procedure. Specifically this approach is used to determine the success of radiation therapy process estimating the final dose delivered to the target volume, based on the soft computing technique of FCMs. Furthermore a two-level integrated hierarchical structure is proposed to supervise and evaluate the radiotherapy process prior to treatment execution. The supervisor determines the treatment variables of cancer therapy and the acceptance level of final radiation dose to the target volume. Two clinical case studies are used to test the proposed methodology and evaluate the simulation results. The usefulness of this two-level hierarchical structure discussed and future research directions are suggested for the clinical use of this methodology.     

An automated flow-batch analyzer based on spectro- photometry for the determination of nitrite

An automated flow-batch analyzer (FBA) based on spectrophotometry was developed for the determination of nitrite (NO2?) in environmental waters. The FBA consists of a homemade flow cell, light source, detector and a mini-syringe pump, which was controlled by self-designed software written in LabVIEW. Two LEDs and a light-to-voltage converter were used as the light source and detector respectively. The chemical detection method was based on spectrophotometry and modified Griess reaction. With the optimized conditions, the limit of detection (LOD) was 0.018 µmol?L-1 and the relative standard deviations (RSDs) at different concentrations (0—12 µmol?L-1) were 0.54%—3.63% (n=3). Measurements of different aqueous samples (n=21) showed no significant difference between results obtained by developed FBA and a commercial spectrophotometer.     

基于北斗系统的装甲车辆信息监控系统研究

通过对北斗卫星导航系统的功能、通信性能的分析,介绍了基于北斗系统的装甲车辆信息监控系统。系统通过车载北斗系统、传感设备分别采集车辆位置信息和状态信息,将各种数据信息进行封装,并利用北斗系统作为通信链路,发送相关信息至控制中心,实现车辆信息监控。     

Quantum efficiency and formation of the emission line in light-emitting diodes based on InGaN/GaN quantum well structures

The spectra of electroluminescence, photoluminescence, and photocurrent for the In_0.2Ga_0.8N/GaN quantum-well structures are studied to clarify the causes for the reduction in quantum efficiency with increasing forward current. It is established that the quantum efficiency decreases as the emitting photon energy approaches the mobility edge in the In_0.2Ga_0.8N layer. The mobility edge determined from the photocurrent spectra is E _me = 2.89 eV. At the photon energies hv > 2.69 eV, the charge carriers can tunnel to nonradiative recombination centers with a certain probability, and therefore, the quantum efficiency decreases. The tunnel injection into deep localized states provides the maximum electroluminescence efficiency. This effect is responsible for the origin of the characteristic maximum in the quantum efficiency of the emitting diodes at current densities much lower than the operating densities. Occupation of the deep localized states in the density-of-states “tails” in InGaN plays a crucial role in the formation of the emission line as well. It is shown that the increase in the quantum efficiency and the “red” shift of the photoluminescence spectra with the voltage correlate with the changes in the photocurrent and occur due to suppression of the separation of photogenerated carriers in the field of the space charge region and to their thermalization to deep local states.     

Improvement of the input power dynamic range for wavelengthconverters based on cross-gain modulation employing a probe powercontrol loop

A technique for improving the input power dynamic range of wavelength converters based on cross-gain modulation in a semiconductor optical amplifier is presented. By experimentally investigating the effect of pump and probe powers on the operating performance in terms of power penalty for a conventional wavelength converter, we show that the optimal performance depends on the ratio of pump and probe powers coupled into the semiconductor optical amplifier in a certain input power range. Based upon the experimental result, a wavelength converter with a wide dynamic range has been proposed, in which the probe power is automatically adjusted to have the power proportional to the pump power. We show that a dynamic range of >20 dB is achievable for a 2.5 Gbit/s signal at a 2-dB penalty     

Experimental studies of the adequacy of laser simulations of dose rate effects in integrated circuits and semiconductor devices

Comparative experimental studies of the responses of typical representatives of integrated circuits (ICs) and semiconductor devices (SDs) with various designs to high-energy pulsed ionizing radiations from simulation facilities and laser simulators have been carried out. The differences between the hardness values under exposure to radiations from simulation facilities and laser simulators have been found to be no larger than the dosimetry errors when the power supply ionization current calibration procedure is used. The shapes of power supply ionization currents and output voltages in the ICs are almost identical qualitatively. The levels and patterns of the functional IC failures are completely identical for both types of radiation sources. As a result, we have proven that a joint application of simulation facilities and laser simulators provides a rational combination of the reliability and efficiency of testing ICs and SDs for hardness to dose rate.     

Influence of hydrogen on local phase separation in InGaN thin layers and properties of light-emitting structures based on them

Results of studies of hydrogen addition during the growth of thin (∼2–3 nm) InGaN layers on their structural properties and properties of light-emitting structures that contain InGaN/GaN heterostructures in the active region are reported. It is shown that, with the known effect of a decrease in the average content of In, hydrogen addition leads to varying the local phase separation in the InGaN layers. Hydrogen addition during the growth of the InGaN layers initially causes suppression of the local phase separation, while hydrogen addition during interruptions of the growth after deposition of the InGaN films leads to a decrease in the size of the formed local In-enriched regions and to a certain increase in the local content of the In atoms.     

基于单片机的公交车自动报站系统的设计与实现

针对当前公交车手动电子报站的不足,设计了一种新型自动报站系统。通过将单片机控制技术、数字语音技术和短距离无线通信技术相结合来实现自动报站的功能,并给出了系统的总体结构和软硬件设计。该方案可以降低司机的工作强度,提高车辆运行的安全性,且成本较低,具有较强的实用价值。     

Experimental study of frequency multipliers based on a GaAs/AlAs semiconductor superlattices in the terahertz frequency range

Frequency multipliers based on a GaAs/AlAs semiconductor quantum superlattice have been experimentally studied. The power spectrum of the harmonics in the output signal from a multiplier with an input-signal frequency of 140–160 GHz has been measured. Planar diodes with a small active region (an area of 1–2 μm²) have been used in this study. For fabrication of the diodes, structures of heavily doped superlattices with the miniband width 24 meV have been used, these structures were grown by the molecular-beam epitaxy method. Measurements have been conducted using a BOMEM DA3.36 Fourier spectrometer equipped with a detector based on a bolometer cooled to the temperature of liquid helium. The results of the measurements have been used to plot the dependences of the power of the harmonics on the frequency in the range from 0.4 to 8.1 THz. It has been found that the character of the microwave-power distribution over the number of harmonics is close to the spectrum of a sequence of sign-alternating pulses which appear in the diode circuit when the applied voltage of the input signal exceeds the threshold of the diode. The minimal time of establishment of the pulse front and pulse duration are equal to 123 and 667 fs, respectively.     

无线网络交通气象站风速测量系统设计

介绍了以压力传感器为检测器件的风速测量原理,提出了一种基于CC2420的无线网络风速测量系统的设计方案,详细描述了硬件电路设计和软件实现。系统以Atmega128高性能单片机和CC2420无线传感模块为核心,通过对相关气象数据的采集、处理、和其他网络节点的通信,实现风速的智能化测量。系统具有精度高、功耗低、可靠性强等特点。     

基于nRF24L01和IAP15W4K58S4的粮仓环境监测系统的设计

针对目前粮仓环境监测系统存在布线繁琐、安装不便、维护麻烦等问题,提出了一种基于nRF24L01和IAP15W4K58S4的粮仓环境监测系统的设计方案。nRF24L01是一种新兴的无线通信技术,具有低功耗、高传输速率、低成本等特点,可直接与各种单片机连接使用,且编程简单;IAP15W4K58S4是一款高性价比单片机,价格便宜且功能强大。该监测系统由传感器节点和环境监测节点两部分构成,传感器节点将检测到的温度、湿度和气体等数据发送给环境监测节点,环境监测节点将这些数据处理后,经由串口传输给PC机来显示。经实际测试表明,该系统能稳定运行,并较好地应用于环境监测领域。     

基于IAP15W4K58S4单片机管道内钢珠运动测量系统的设计

文章设计了一个管道内钢珠运动测量装置,通过检测进入管道钢珠的运动状态,实现了钢珠个数、运动方向、周期及管道放置角度的测量。本系统以IAP15W4K58S4单片机为核心,利用电感式接近开关传感器的电涡流效应,将检测到的信号发送至单片机进行分析,计算出管道放置的角度,并送至LCD液晶显示屏显示。     

基于Wi-Fi和基站信号强度的室内定位系统设计与实现

分析了现有的室内定位技术,对室内定位信号测量技术、位置估算技术、定位采用的信号以及典型的室内定位系统作了详细阐述。提出了基于Wi-Fi和基站信号强度的室内定位系统架构,并从功能实现和软件架构2个方面说明了该系统的组成,最后经实验证明该系统能够实现及时稳定的室内定位和位置服务。     

Investigation of GaAs/AlGaAs quantum cascade structures by optical methods based on hot luminescence in the near-infrared range

The time-resolved photoluminescence of GaAs/AlGaAs quantum-cascade structures under intense pulse excitation is studied. Aside from optical transitions between the ground electron and hole states of a system of two tunnel-coupled quantum wells, the photoluminescence spectrum at short times after the excitation pulse exhibits features corresponding to transitions between the excited states of these wells, which are not observed in time-integrated photoluminescence spectra. It is shown that, due to a high pump level, the electron gas is initially strongly heated, which makes it possible to observe band-to-band transitions between both the ground and excited states. Nonequilibrium carriers cool down with a characteristic relaxation time of ～125 ps.     

多传感器目标综合识别在VTS系统中应用研究

介绍了采用两部雷达、一套CCTV系统和一套VHF语音系统组成的VTS系统，利用多传感器对目标进行综合识别的方法，实现对重点监视水域目标的管理与控制，对多传感器目标识别的方法进行了研究验证，取得了良好的效果。