Ultra Wide Band (UWB) Horseshoe Antenna for Future Cognitive Radio Applications

In this paper, an UWB micro-strip antenna design has been proposed which is suitable for future cognitive radio applications. The geometry of proposed antenna is composed of two semi-circles with their interior modified in order to achieve higher impedance bandwidth. The semi-etched ground provides further bandwidth enhancement. The proposed antenna is fabricated on an inexpensive dielectric substrate FR-4 with relative permittivity of 4.4 and thickness of 1.6 mm. The overall dimensions of UWB antenna are 60?×?60?×?1.6 mm and have a bandwidth of 5.7 GHz. The designed antenna covers the most commonly used wireless communication bands such as DCS-1800, ISM bands, GPS, Wi-MAX, WLAN, 3G, 4G, etc. The design process and the variations in antenna’s performance due to different parameters has been discussed. The design and simulation of the antenna are carried out in the Ansys Electronic Desktop HFSS. The measured results are in good agreement with simulated results and design theory which shows that the proposed antenna is good candidate for the UWB applications.

     

The effect of filler concentration on the electrical,thermal, and mechanical properties of carbon particle and carbon fiber‐reinforced poly(styrene‐co‐acrylonitrile) composites

Composite materials of poly (styrene‐co‐acrylonitrile) (luran) matrix with carbon fibers (CF)/carbon particles (CP) were prepared and their properties were evaluated. The mechanical and thermal properties of these composites were studied by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). Although, by increasing the filler concentration no significant difference was found in melting and crystallization temperatures of the luran. The storage and tensile modulus of the composites increased linearly with filler concentration up to 40 wt % that was approximately three times higher than that of the virgin luran. There is a shift in glass transition temperature of the composite with increasing the filler concentration and the damping peak became flatter that indicated the effectiveness of the filler–matrix interaction. The volume resistivity and thermal conductivity (TC) of the composites were also measured. At a given carbon filler content the CF–Luran composites have much less volume resistivity as compared to CP–Luran composites. The decreased percolation threshold and volume resistivity in case of CF–Luran composites indicated that conductive paths existed in the composites. The conductive pathways were probably formed through interconnection of the carbon fillers. The volume resistivity was also decreased as a function of temperature. The thermal conductivity was increased linearly as a function of temperature with increasing filler concentration up to 40% of CF and CP. This increase was more profound in case of CF–Luran as compared to CP–Luran composites. This was owing to greater thermal networks of fibers as compared to particles. POLYM. COMPOS., 28:186–197, 2007. © 2007 Society of Plastics Engineers     

High performance thermoplastic composites: Study on the mechanical,thermal, and electrical resistivity properties of carbon fiber‐reinforced polyetheretherketone and polyethersulphone

High temperature processing thermoplastic polymers, polyetheretherketone (PEEK) and polyethersulphone (PES), were melt blended with carbon fibers (CFs) to make composites. These composites were investigated for their mechanical, thermal, and electrical properties. Mechanical properties that are expressed in terms of storage modulus, loss, and damping were enhanced with the addition of CFs. Thermal properties were determined by DSC and TGA. These methods help to understand the effects of fiber content and fiber–matrix adhesion in the composites. Composites were also tested for their electrical and thermal conductivity because CFs leave the composites thermally and electrically conductive. CFs enhanced the crystallinity of the PEEK appreciably that in turn influenced thermal conductivity, electrical resistivity, and the stiffness of PEEK/CF (composites of PEEK with CFs). PES/CF (composites of PES with CF) shows a different behavior due to the amorphous nature of PES. The work involves one filler and two different matrices, and so it provides an interesting comparison of how matrix morphology can influence the properties of composites. POLYM. COMPOS. 28:785–796, 2007. © 2007 Society of Plastics Engineers.     

An adaptive key selection method for the multilevel index model for effective service management in the cloud

The growing number of services processed and stored in the cloud has led to difficulties in managing and discovering the required services efficiently. Multilevel index model is an efficient method to manage and retrieve services in service repositories. When adding a new service to a multilevel index model, a key needs to be selected for the service, but existing key selection methods cannot adapt to the situation that hot services change over time. To address this problem, this article proposes an adaptive key selection method to improve the efficiency of service retrieval. However, the service addition operation of the adaptive key selection method is inefficient in the multilevel index model. For this reason, this article improves the multilevel index model by introducing local equivalence partition. This indexing model improves the service addition efficiency of the adaptive key selection method without affecting the service retrieval efficiency. It is experimentally demonstrated that the retrieval and addition efficiencies of the adaptive key selection method are close to the ideal state optimum under the multilevel index model with local equivalence partitioning.     

NoC映射问题中的列举路径分配算法

映射和路径分配是片上网络在编译过程中两个相辅相成的重要步骤,对系统的通信功耗影响很大。该文针对片上网络映射过程中现有路径分配法寻径不充分的问题,提出了一种基于列举的路径分配算法。该算法通过列举各通信流的所有合法路径,对路径的各种组合方式进行充分搜索。同时将路径分配算法应用到禁忌搜索映射算法中,并对映射算法做了改进,以适应路径分配算法。仿真结果表明,基于列举的路径分配算法提高了满足约束的路径被搜索到的概率,优化了映射算法的结果。     

一种高速DSP中延迟优化的乘累加单元的设计与实现

乘累加单元是任何数字信号处理器(DSP)数据通路中的一个关键部分.多年来,硬件工程师们一直倾注于其优化与改进.本文描述了一种速度优化的乘累加单元的设计与实现.本文的乘累加单元是为一种高速VLIW结构的DSP核设计,能够进行16×16 40的无符号和带符号的二进制补码操作.在关键路径延迟上,本文的乘累加单元比其他任何使用相同或不同算数技术实现的乘累加单元都更优.本文的乘累加单元已成功使用于synopsys的工具,并与synopsys的Design Ware库中相同位宽的乘累加单元比较.比较结果表明,本文的乘累加单元比Design Ware库中的任何其他实现都要快,适合于在需要高吞吐率的DSP核中使用.注意:比较是在Design compiler中使用相同属性和开关下进行的.     

Micronutrient fortification of wheat flour: Recent development and strategies

Deficiencies of iron, zinc and vitamin A have been a focus of the governments and world organizations for decades and extensive efforts are being made to address this malnutrition. Being a popular and most common dietary staple of the population living in sub-continent and developing countries, wheat flour (WF) has gained a significant attention as a suitable vehicle for micronutrient fortification. Fortification of wheat flour has been established as an appropriate strategy to curtail micronutrient deficiencies especially in the developing economies. Extent of the prevalence of micronutrient deficiencies, their consequences, selection of a suitable vehicle, choice of fortificants and their levels and storage stability, acceptability and bioavailability of iron and zinc fortified WF are the key points of discussion in the current review. This review further highlights multifaceted issues pertaining to the appropriateness and suitability of fortification over other intervention strategies, ecological needs and fortification success stories and advantages of simply adding fortificants to flour to meet nutritional requirements of vulnerable groups. The authors have attempted to encompass the subject matter based on their research endeavors made in this direction.     

Moisture and Temperature Response of Structural and Lithology based Thermophysical and Energy Saving Traits of Limestone using Experimental and Least-Square Fitting Methods

Thermophysical analysis of the crustal rocks is important for heat transfer determination and insulation purposes to save energy in buildings.In the presented w...     

miRNAs in Regulation of Tumor Microenvironment,Chemotherapy Resistance,Immunotherapy Modulation and miRNA Therapeutics in Cancer

miRNAs are 20–22 long nucleotide non-coding ribonucleic acid molecules critical to the modulation of molecular pathways. Immune evasion and the establishment of a suitable tumor microenvironment are two major contributors that support tumor invasion and metastasis. Tumorigenic miRNAs support these two hallmarks by desensitizing important tumor-sensitive regulatory cells such as dendritic cells, M1 macrophages, and T helper cells towards tumors while supporting infiltration and proliferation of immune cells like Treg cells, tumor-associated M2 macrophages that promote self-tolerance and chronic inflammation. miRNAs have a significant role in enhancing the efficacies of immunotherapy treatments like checkpoint blockade therapy, adoptive T cell therapy, and oncolytic virotherapy in cancer. A clear understanding of the role of miRNA can help scientists to formulate better-targeted treatment modalities. miRNA therapeutics have emerged as diverse class of nucleic acid-based molecules that can suppress oncogenic miRNAs and promote the expression of tumor suppressor miRNAs.     

Cloud‐based decision support system for the detection and classification of malignant cells in breast cancer using breast cytology images

The advancement of computer‐ and internet‐based technologies has transformed the nature of services in healthcare by using mobile devices in conjunction with cloud computing. The classical phenomenon of patient–doctor diagnostics is extended to a more robust advanced concept of E‐health, where remote online/offline treatment and diagnostics can be performed. In this article, we propose a framework which incorporates a cloud‐based decision support system for the detection and classification of malignant cells in breast cancer, while using breast cytology images. In the proposed approach, shape‐based features are used for the detection of tumor cells. Furthermore, these features are used for the classification of cells into malignant and benign categories using Naive Bayesian and Artificial Neural Network. Moreover, an important phase addressed in the proposed framework is the grading of the affected cells, which could help in grade level necessary medical procedures for patients during the diagnostic process. For demonstrating the e effectiveness of the proposed approach, experiments are performed on real data sets comprising of patients data, which has been collected from the pathology department of Lady Reading Hospital of Pakistan. Moreover, a cross‐validation technique has been performed for the evaluation of the classification accuracy, which shows performance accuracy of 98% as compared to physical methods used by a pathologist for the detection and classification of the malignant cell. Experimental results show that the proposed approach has significantly improved the detection and classification of the malignant cells in breast cytology images.