A small microstrip patch antenna with a convenient tuning option

The paper addresses two aspects of resonant microstrip patch antennas, namely, miniaturization and resonant frequency tuning. First, a patch geometry which allows a controllable size reduction over a limited range is presented. The basic shape is circular with slits cut into it. Modification of the slit geometry leads to both linear as well as circular polarized (CP) operation. Second, the use of another patch of a specific shape as a superstrate layer in a stacked configuration allows tuning over a relatively large frequency range as compared to the patch bandwidth. Tuning is accomplished by a simple rotation of the superstrate layer. The use of another superstrate layer allows tunable CP operation. Details on the antenna characteristics have been worked out for two examples, and computations have been compared with measurements where possible. Some design guidelines have also been included     

Influence of fatty acids in waste cooking oil for cleaner biodiesel

Physiochemical properties of biodiesel, a sustainable and green alternative fuel produced from renewable resources, are greatly influenced by the structural features of polyunsaturated, monounsaturated and saturated fatty acids. Two feedstock oils, potentially contribution to cleaner technologies, refined cooking oil and waste cooking oil derived from palm olein have been studied. Fatty acid compositions of the refined cooking oil and waste cooking oil were analysed and confronted with other literature sources. Critical parameters such as cetane number (CN), iodine value, cold filter plugging point (CFPP) and oxidation stability (OS) were correlated with long-chain saturated factor and degree of unsaturation (DU) of fatty acid to match the international standards of cleaner biodiesel. OS in biodiesel has been met with the absence of linolenic acid. High saturated fatty acid provides high CN. The iodine value of feedstock oil met the European standard where the DU of the oils was less than 138. However, CFPP of refined cooking oil and waste cooking oil did not meet the demanding Spanish regional (RD 61/2006) standard due to the presence of stearic and palmitic acid, which tended to clog the fuel filter by precipitating while the biodiesel becomes cool. With the proposed triangular chart for biodiesel properties prediction, potential biodiesel fuels from various feedstock oils can be analysed.     

Efficient algorithms for a class of partitioning problems

We address the problem of optimally partitioning the modules of chain- or tree-like tasks over chain-structured or host-satellite multiple computer systems. This important class of problems includes many signal processing and industrial control applications. Prior research has resulted in a succession of faster exact and approximate algorithms for these problems. We describe polynomial exact and approximate algorithms for this class that are better than any of the previously reported algorithms. Our approach is based on a preprocessing step that condenses the given chain or tree structured task into a monotonic chain or tree. The partitioning of this monotonic task can then be carried out using fast search techniques     

Ray analysis of a class of hybrid cylindrical aircraft wings

A new approach to the modelling of aircraft wings, based on the combination of hybrid quadric (parabolic and circular) cylinders, has been presented for electromagnetic applications. Closed-form expressions have been obtained for ray parameters required in the high-frequency mutual coupling computation of antenna pairs located arbitrarily on an aircraft wing     

A network flow model for load balancing in circuit-switchedmulticomputers

In multicomputers that utilize circuit switching or wormhole routing, communication overhead depends largely on link contention-the variation due to distance between nodes is negligible. This has a major impact on the load balancing problem. In this case there are some nodes with an excess load (sources) and other with a deficit load (sinks). A matching of sources to sinks is required to avoid contention. The problem is made complex by the hardwired routing on currently available machines: The user can control only which nodes communicate but not how the messages are routed. Network flow models of message flow in the mesh and the hypercube have been developed to solve this problem. The crucial property of these models is the correspondence between minimum cost flows and correctly routed messages. To solve a given load balancing problem, a minimum cost flow algorithm is applied to the network. This permits the efficient determination of a maximum contention free matching of sources to sinks that, in turn, tells how much of the given imbalance can be eliminated without contention     

A new algorithm for the normal distribution function

In this paper new algorithms for the rapid, efficient and accurate evaluation of the standard normal integral and its tail are developed. It is shown how the accuracy of the computation can easily be improved so as to achieve machine accuracy for the particular computer being used.     

Site shielding of earth-station antennas

This paper concerns interference in satellite earth stations, due to microwave links sharing the same frequency band, and its solution by site shielding. The uniform theory of diffraction (UTD) has been used to analyze the near field of a parabolic-reflector antenna. An extension of the UTD, in which the influence of the surface impedance is taken into account, has been applied, to calculate the diffraction from the top of the barrier. The theoretical model has been verified in a field-measurement exercise, using a three-meter earth-station antenna, located behind an existing free-standing concrete wall, with a simulated source of interference. The undesirable effects of the barrier on the gain, noise temperature, and the radiation pattern have been studied, and criteria for the clearance of the main beam have been established. Methods of improving shielding effectiveness using absorbing materials and, also, specially shaped diffracting edges have been studied, as well. Laboratory measurements of the diffraction loss of absorbers have been made, and relative advantages are presented. Design guidelines have also been given     

Influence of fatty acids content in non-edible oil for biodiesel properties

Physical and chemical properties of biodiesel are influenced by the structural features of fatty acid, such as with saturated, monounsaturated and polyunsaturated fatty acids. In this study, seven non-edible oils have been selected, which include waste cooking oil derived palm olein, Calophyllum inophyllum, jatropha oil, castor oil, rubber seed oil, kapok seed oil and karanja oil. The critical parameters, e.g. cetane number (CN), iodine value (IV) and oxidation stability (OS) of biodiesel were correlated with the degree of unsaturated (DU) fatty acid, whereas the cold filter plugging point (CFPP) was correlated with the long chain saturated factor (LCSF). To meet the minimum EU requirement of EN 14214 of the critical parameter, the DU value of the CN was ≤133.5, IV ≤123.2 and OS ≤98.9. The LCSF values satisfied the Spanish regional standard—RD 61/2006 in summer (0 °C) at ≤8.4 and winter (?10 °C) at ≤0.1 of the CFPP. Based on the composition of the saturated, monounsaturated and polyunsaturated fatty acids, a triangular chart for the biodiesel property prediction was developed. This can then be used as a reference for non-edible oils.     

Surface‐functionalised hybrid nanoparticles for targeted treatment of cancer

Cancer is a leading cause of death worldwide. Despite the great advancement in understanding the pharmacology and biology of cancer, it still signifies one of the most serious human‐health related problems. The current treatments for cancer may include surgery, radiotherapy, and chemotherapy, but these procedures have several limitations. Current studies have shown that nanoparticles (NPs) can be used as a novel strategy for cancer treatment. Developing nanosystems that allow lower doses of therapeutic agents, as well as their selective release in tumour cells, may resolve the challenges of targeted cancer therapy. In this review, the authors discuss the role of the size, shape, and surface modifications of NPs in cancer treatment. They also address the challenges associated with cancer therapies based on NPs. The overall purpose of this review is to summarise the recent developments in designing different hybrid NPs with promising therapeutic properties for different types of cancer.Inspec keywords: tumours, reviews, patient treatment, nanomedicine, surgery, radiation therapy, cellular biophysics, nanobiotechnology, nanoparticles, cancerOther keywords: current treatments, cancer treatment, targeted cancer therapy, cancer therapies, surface‐functionalised hybrid nanoparticles, targeted treatment, serious human‐health related problems