Joint Access Point Placement and Channel Assignment for 802.11 Wireless Local Area Networks

To deploy a multi-cell IEEE 802.11 wireless local area network (WLAN), access point (AP) placement and channel assignment are two primary design issues. For a given pattern of traffic demands, we aim at maximizing not only the overall system throughput, but also the fairness in resource sharing among mobile terminals. A novel method for estimating the system throughput of a multi-cell WLAN is proposed. An important feature of this method is that cochannel overlapping is allowed. Unlike conventional approaches that decouple AP placement and channel assignment into two phases, we propose to solve the two problems jointly for better performance. Due to the high computational complexity involved in exhaustive searching, an efficient local searching algorithm, called patching algorithm, is also designed. Numerical results show that for a typical indoor environment, the patching algorithm can provide a close-to-optimal performance with much lower time complexity.published_or_final_versio

Production of high temperature grease from waste lubricant sludge and silicone oil

This research was carried out to study the production of high temperature grease from waste lubricant sludge and silicone oil. The effects of different ratios of waste lubricant sludge to fumed silica and mixing time on grease characteristics were investigated. The ratios of waste lubricant sludge and fumed silica used were 100:0, 90:10, 80:20, 70:30, 60:40, 50:50 and 40:60. In terms of mixing time, it was varied at 1, 2, 3, 4 and 5 hours. Throughout the experiment, the grease was prepared by using the heating and mixing technique. The grease produced was analysed according to the ASTM and NLGI standard via penetration test, dropping point test, copper corrosion test, FTIR and AAS.Fourier transform infra red (FTIR) analysis was carried out to study on the functional groups present in the grease. Atomic absorption spectroscopy analysis was also carried out to determine the concentration of a specific metal element in the grease. The results showed that the grease produced with a minimum ratio of fumed silica to sludge (10:90) was able to produce high temperature grease with a dropping point of 272.5.C.Further analysis verified that the grease is a high temperature grease, has worked penetration of 270-290 which makes the grease fall into the common grease category, has a low tendency to corrode copper and very little metal element was present in the grease. It can be concluded that the ratio of fumed silica to sludge and the mixing time of the grease produced significant effect on worked penetration and dropping point of the grease

Retaining customer loyalty when moving to a new location: A case study on a small restaurant

The restaurant was opened recently. Due to the reconstruction of the building, the owner is considering moving the restaurant to a new location. The research aims to discuss how location and other factors affect customer loyalty and how to retain customers when moving to a new location. To analyse and explain the aims, the researcher conducted an interview with the owner of the restaurant and used two questionnaires, one for the customers of the restaurant (30 sampling) and another for potential restaurant goers (30 sampling). The research method used a combination of quantitative and qualitative methods. The research is still under development and not yet complete, therefore only part of results and recommendations are illustrated. The restaurant has a relatively large group of loyal customers. Location plays only a small role in customer behaviour for choosing a restaurant. Accessibility, surroundings and affordability need to be considered when choosing location

Bilateral retinal pigment epithelial rips in hypertensive choroidopathy

AbstractSevere systemic hypertension can cause significant damage to the eye. Although hypertensive retinopathy is a well-known complication, hypertensive optic neuropathy and hypertensive choroidopathy are much less common. The aim of this article is to report an unusual case of hypertensive choroidopathy with bullous exudative retinal detachments in both eyes. The retinal detachments spontaneously resolved after blood pressure was controlled. However, multiple large retinal pigment epithelial (RPE) rips were found in both eyes. These RPE rips may be related to severe choroidal ischemia, and their locations may be compatible with the watershed zones of the choroidal perfusions

Association of breastfeeding and three-dimensional dental arch relationships in primary dentition

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