Explore the vast range of titles available.

The rectenna as a device, is critical for achieving long-distance wireless power transfer. The centrality of this study is focused on adding to the collective knowledge of the subject matter, by providing a new perspective in terms of an alternative design for the antenna component of the rectenna. Essentially, this study features a novel \"3-point star\" design which was simulated in comparison with the conventional square microstrip patch antenna design. Both designs (i.e., operating at the Wi-Fi band 2.4 GHz), were assessed in terms of simulated performance parameters: gain, directivity, return loss, radiation pattern, and efficiency. From the simulation results, the proposed \"3-point star\" design, though slightly less efficient exhibited improved performance over the conventional square patch alternative, in terms of gain, directivity, and return loss. For the rectifying component, a greinacher voltage-doubler (with two HSMS2820 diodes), was designed separately and simulated over a range of input power levels (10dBm-34dBm), for 220-Ω, 380-Ω and 810-Ω load resistances, respectively. A maximum conversion efficiency of 88.02% was achieved at 28dBm for an 810 Ω load resistance. All design simulations were executed using Advanced Design System (ADS) software.

The present situation of power generation in Nigeria obviously represents a challenge to our ability for rethinking the delivery of energy at maximum efficiency. Previous research on the existing Nigerian 330-kV network grid, recommended that the network be transformed from radial to ring because of high losses inherent in it and the voltage insecurity. In this study, the existing 330-kV network was reconfigured based on the identified regions mapped out for upgrade to form a ringed 750-kV super grid. The bus voltages of some of the buses in the existing 330-kV were upgraded to 750-kV and new transmission lines added to create an integrated super grid with a ring structure as compared to the radial nature of the existing 330-kV grid. These proposed buses have been selected for upgrade based on the fact that they are positioned in critical areas within the topology of the grid that transforms the existing radial structure to a ring one. The method is also cheaper than making the entire network a 750-kV system. Load-flow analysis was carried out on the existing 330-kV Nigerian Grid and the proposed Nigerian 750-kV integrated into the existing grid using Newton–Raphson algorithm. The results analysis of the new network revealed a significant reduction of 30.2% power loss. This was validated using the code-based MATLAB and Power World Simulation model-based software. Contingency analysis was also carried out on both grids using the Power World Simulator. The study revealed that the 750-kV super grid was able to mitigate the losses experienced on the existing grid significantly with better voltage profiles in all the buses. It also revealed that the new network (330-kV and 750-kV integrated) performed better to the single line contingency analysis with less violations occurring and no unsolvable cases.

According to [3], availability of telecommunications services provide easy access to information, but in recent time, mobile devices like smartphones are used more frequently for various applications other than telecommunication [4]. [...]different sectors of society are adopting the use of mobile device technology for a wide range of services and this trend has necessitated the restructuring of the educational system. [...]ResearchGate is therefore, primarily a social networking site for academics [19] that has additional or supporting features. According to Acharya, \"information had very strong geographical boundaries\" [27] and it is clear that Google Scholar is on the quest to solve this as much as it can.

The advancement of technology has brought about the need for industrial innovation. One area where innovation is required in a developing country is in the retail industry (this is the focus point of this project) where the present system that is the barcode technology is old and archaic. This project is based on the use of Radio Frequency Identification (RFID) technology to create a faster, easier and more secured checkout system. This paper showcases the development of a miniature RFID desktop application that can be used for registering items coming into a shopping mall, checking out of goods bought from the shopping mall and the detection of an attempt to steal goods from the shopping mall, using both C# programming language and MySQL for the database management.

The cumulative number of historical and recent power system outages substantiates the fact that further studies are necessary for an improved solution to the issue of voltage instability on the grid and the subsequent system collapse. Voltage collapse is a serious reliability issue which inhibits the objective of running a reliable and secure power system network. In this study, a new line stability index (NLSI_1) for predicting voltage collapse is presented.  The new index considers a switching logic which is derived from the difference of voltage angle between the two load buses. The index is deployed for performance analysis using the 28-bus, 330-kV Nigeria National Grid (NNG).  The simulation implemented in MATLAB shows that the index gives the same results as Line stability index (Lmn) and Fast Voltage Stability Index (FVSI) indices. The base case and the contingency scenarios were considered during the simulation. The base case analysis using the NNG values of all the three indices FVSI, Lmn, and NLSI_1 for simulation generates a value less than one for the entire lines which implies that the NNG is stable in this mode. The values of the three indices are almost the same, which confirms the accuracy of the novel index developed. The analysis for the contingency case reveals that the load bus 16 (Gombe) which has the lowest, maximum permissible reactive load of 139.5MVAR is the weakest; also power line 16-19 is identified as the critical line. The result of the simulation confirms that the accuracy was improved by using NLSI_1.

[...]there will be need for expansion when load demand equals or greater than the supply power from generation stations. According to CIRED (1999), there is no consensus yet on the generally acceptable definition of DG. [...]it can be said that Installation of distributed generation permits the utilization of freely available fuel opportunities [6]. Though many researchers did not specify the DG technology employed, their analyses prove that RES were not considered. [...]recommendations for further studies in this area of research will include integration of RES into the grid, consideration for islanding in integrating DG into the grid and protection coordination of a network with DG(s).

Epileptic power supply, scarcity of fuel, and the ever increasing demand for power supply have given rise to the development of several off-grid and on-grid power alternatives. A single phase to three phase rotary phase converter is a machine that can generate three phase power supply from an existing single phase source. This is a cheap means of generating three phase power especially in some residential environments where access to three phase power is limited. Some home equipment such as air conditioners and refrigerators run on three phase power also workshop owners and technicians have need to operate three phase machinery which may include table saw, drilling machine, lathe machine, and any machinery that runs on three phase power.

Food is a basic necessity of life. It is the means by which man is nourished and strengthened to carry out his daily activities. The need for food for the upkeep of man has placed agriculture at the helm of man’s affairs on earth. With a rapidly increasing population on earth, man has invented newer and innovative ways to cultivate crops. This cultivation is mainly concentrated in rural areas of countries around the world; but with the massive urbanization happening in the world today; it is becoming increasingly difficult to have enough agricultural produce that will cater for the massive population. Taking Nigeria as a case study, the increased urbanization has placed a massive demand on land, energy and water resources within urban areas of the country. Majority of the food consumed in the urban areas is cultivated in the rural areas. This system however requires longer transportation times from rural areas to urban areas which lead to contamination and spoilage in many instances. This research paper provides a solution in which food crops can be cultivated easily in urban areas by planting in vertically stacked layers in order to save space and use minimal energy and water for irrigation.

: Etching is a subtractive method that is used for the production of printed circuit boards (PCBs), where acid is been used to remove unwanted copper from a prefabricated laminate [1]. The manual method of doing this can only be used for a small number of boards and is likely to be messy [2]. Besides this, exposure to some certain kinds of etchants may have adverse effects on one’s health. On the other hand, the machines available to do this provide a cleaner and faster means and can etch many boards at a time but they are very expensive. This usually discourages their purchase among small scale Printed Circuit Board (PCB) manufacturers. But the automated etching system presented here aims at providing a method of carrying out the etching process for a PCB board in a simple, clean, safe and cost effective way. The printed circuit board is mechanically designed to support and electrically to connect electronic components using conductive tracks, pads and features etched from copper sheets laminated onto a non-conductive substrate.