DVCC-Based Non-linear Feedback Neural Circuit for?Solving System of Linear Equations

A neural circuit to solve a system of simultaneous linear equations is presented. The circuit employs non-linear feedback to achieve a transcendental energy function that ensures fast convergence to the exact solution while enjoying reduction in hardware complexity over existing schemes. A new building block for analog signal processing, the digitally controlled differential voltage current conveyor (DC-DVCC) is introduced and is utilized for the non-linear synaptic interconnections between neurons. The proof of the energy function has been given and it is shown that the gradient network converges exactly to the solution of the system of equations. PSPICE simulation results are presented for linear systems of equations of various sizes and are found to be in close agreement with the algebraic solution. The use of CMOS DC-DVCCs and operational amplifiers facilitates monolithic integration.     

Electromagnetic surface waves supported by a half-space of a counterstreaming plasma

The characteristics of electromagnetic surface waves supported by a plane interface separating a semi-infinite region of free space from another semi-infinite region consisting of a plasma counterstreaming parallel to the interface are investigated for the case in which the wave is progressing parallel to the direction of the streams. The behaviour of the surface waves is quite different from the case in which the plasma is stationary. The surface waves exist for all frequencies. The phase velocity of the surface wave is equal to the electromagnetic wave velocity in free space for very low frequencies, decreases monotonically as the frequency is increased and asymptotically approaches the velocity of the stream for very high frequencies. The surface waves are always stable. In contrast to on unbounded counterstreaming plasma which gives rise to instability for the plane longitudinal wave progressing parallel to the streams, a half-space of counterstreaming plasma does not give rise to any instabilities for waves progressing parallel to the streams.     

U-slot Loaded Half Disk Patch Antenna for Mobile Communications

Theoretical investigations of a U-slot loaded half disk patch antenna are presented using equivalent circuit concept. It is found that the antenna shows dual band characteristics with resonant frequency at 4.76 and 6.79 GHz. The dual nature of the antenna is realized by loading shorting pin with U-slot loaded patch. The lower and upper frequency bands are achieved as 443 and 287 MHz respectively. It is noted that the antenna shows frequency ratio of 1.4.     

端到端网络服务健康度的人工免疫评价模型

从网络多维性能出发,建立了端到端网络服务健康度评价模型(ENHMM).该模型支持动态定制服务评价因子,同时给出基于评价因子的网络性能数据的主动测量方法.在评价算法上,利用了一种新的抗体促进与抑制机制的AiNet网络免疫算法.开发了原型系统对现实网络进行评价,得到了网络服务健康度等级.通过对评价结果的线性回归分析,发现该等级能够准确地反映用户感知的网络质量.     

Tunnel diode-loaded rectangular microstrip antenna for millimeter range

Theoretical investigations conducted for Ge tunnel diode-integrated rectangular patch antenna reveals that such an antenna exhibits frequency tunability with the bias voltage. The Ge tunnel diode-loaded patch can be operated in the millimeter range (51.042-54.013 GHz). The range of frequency obtainable for operation is 2971 MHz. The radiation pattern shows variation with the bias voltage and the radiated power, the beamwidth and the directivity vary inversely with the bias voltage. Thus, the Ge tunnel diode-loaded patch can be used to achieve electronic tuning (BW=5.66%) with the bias voltage.     

浅谈数字机顶盒的利弊和发展

阐述了数字机顶盒在城市家庭收视使用过程中的优缺点,机顶盒使用的技术参数特性,针对机顶盒使用缺陷的具体改进方案,以及数字机顶盒技术在未来的发展趋势。     

数据挖掘算法的评价标准与方法

文章阐述了数据挖掘的定义及所涉及到的基础理论知识，并根据数据挖掘本身的特点，探讨了选择合适挖掘算法的重要性，同时分析提出了数据挖掘算法的评价标准与评估方法。并结合实例作了分析。     

Analysis of L-Shaped Slot Loaded Circular Disk Patch Antenna for Satellite and Radio Telecommunication

In the present paper a dual frequency resonance antenna is achieved by introducing L- shaped slot in circular disk patch. It is analysed by using circuit theory concept. The resonance frequency is found to be 5.087 and 8.455 GHz and the 10 dB bandwidth of the proposed antenna for lower and upper resonance frequency is found to be 4.39 and 4.66 % respectively. It is easy to adjust the higher and lower band by changing the dimensions of notch and slot introduced in the antenna. The frequency ratio is found to be 1.6621. The gain and efficiency of the proposed antenna is found to be 9.50 dB at lower resonance however it is 7.0 dB at upper resonance frequency whereas the efficiency at lower and upper resonance is found to be 94.6 and 88.2 %.The theoretical results are compared with IE3D simulation results which are in good agreement.     

An Organoid for Woven Bone

Bone formation (osteogenesis) is a complex process in which cellular differentiation and the generation of a mineralized organic matrix are synchronized to produce a hybrid hierarchical architecture. To study the mechanisms of osteogenesis in health and disease, there is a great need for functional model systems that capture in parallel, both cellular and matrix formation processes. Stem cell-based organoids are promising as functional, self-organizing 3D in vitro models for studying the physiology and pathology of various tissues. However, for human bone, no such functional model system is yet available. This study reports the in vitro differentiation of human bone marrow stromal cells into a functional 3D self-organizing co-culture of osteoblasts and osteocytes, creating an organoid for early stage bone (woven bone) formation. It demonstrates the formation of an organoid where osteocytes are embedded within the collagen matrix that is produced by the osteoblasts and mineralized under biological control. Alike in in vivo osteocytes, the embedded osteocytes show network formation and communication via expression of sclerostin. The current system forms the most complete 3D living in vitro model system to investigate osteogenesis, both in physiological and pathological situations, as well as under the influence of external triggers (mechanical stimulation, drug administration).     

低初始黏度可控凝胶调堵剂的研制及性能评价

为了满足聚合物驱后深部定点调堵的需求,进一步挖潜剩余油,研发了一种以相对分子质量2500万的部分水解的阴离子型聚合物、金属离子交联剂、调节剂、缓凝剂、增强剂组合的低初始黏度可控凝胶调堵剂体系,对其性能进行了评价。研究结果表明:用现场回注污水配制的配方为500数1000 mg/L聚合物LH2500+1000数2500mg/L交联剂CYJL+200数500 mg/L调节剂(柠檬酸)+100数150 mg/L缓凝剂(亚硫酸钠)+100数200 mg/L增强剂(多聚磷酸钠)的凝胶初始黏度低,在10 mPa·s以内;成胶时间10数40 d内可控,成胶黏度2000 mPa·s以上。体系耐矿化度可达20000 mg/L,应用pH范围为8数9;体系具有较好的岩心封堵性能,对水测渗透率为0.48数3.9μm~2的岩心封堵率均在99%以上,残余阻力系数为95.6数396.1。三层并联岩心实验结果表明该体系对中、低渗透层的污染少,可以满足现场的封堵要求。图2表7参10