Cross-Layer Optimization in OFDM Wireless Communication Network

The wide use of OFDM systems in multiuser environments to overcome problem of communication over the wireless channel has gained prominence in recent years. Cross-layer Optimization technique is aimed to further improve the efficiency of this network. This chapter demonstrates that significant improvements in data traffic parameters can be achieved by applying cross-layer optimization tech- niques to packet switched wireless networks. This work compares the system capacity, delay time and data throughput of QoS traffic in a multiuser OFDM system using two algorithms. The first algorithm, Maximum Weighted Capacity, uses a cross-layer design to share resources and schedule traffic to users on the network, while the other algorithm (Maximum Capacity) simply allocates resources based only on the users channel quality. The results of the research shows that the delay time and data throughput of the Maximum Weighted Capacity algorithm in cross layer OFDM system is much better than that of the Maximum Capacity in simply based users channel quality system. The cost incurred for this gain is the increased complexity of the Maximum Weighted Capacity scheme

Microstructural Evaluation of Aluminium Alloy A365 T6 in Machining Operation

The optimum cutting parameters such as cutting depth, feed rate, cutting speed and magnitude of the cutting force for A356 T6 was determined concerning the microstructural detail of the material. Novel test analyses were carried out, which include mechanical evaluation of the materials for density, glass transition temperature, tensile and compression stress, frequency analysis and optimisation as well as the functional analytic behaviour of the samples. The further analytical structure of the particle was performed, evaluating the surface luminance structure and the profile structure. The cross-sectional filter profile of the sample was extracted, and analyses of Firestone curve for the Gaussian filter checking the roughness and waviness profile of the structure on aluminium alloy A356T6 is proposed. A load cell dynamometer was used to measure different parameters with the combination of a conditioning signal system, a data acquisition system and a computer with visualised software. This allowed recording the variations of the main cutting force throughout the mechanised pieces under different cutting parameters. A carbide inserted tool with triangular geometry was used. The result shows that the lowest optimum cutting force is 71.123 N at 75 m/min cutting speed, 0.08 mm/rev feed rate and a 1.0 mm depth of cut. The maximum optimum cutting force for good surface finishing is 274.87 N which must be at a cutting speed of 40 m/min, 0.325 mm/rev feed rate and the same 1.0 mm depth of cut

Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.

Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability

Leveraging MMW AVE Technology for Mobile Broadband/Internet of Things

Today, almost every individual possesses at least one internet -connected device. According to Cisco, there were over 12.5 billion devices in 2010 alone. It has been predicted that 25 billion devices will be connected by 2015, and so billion devices by 2020; all contributing towards the Internet of Things (loT). This rapid increase exposes the obvious need for enhancements in various underlying technologies. IPv6 for example, has been developed to provide 340 undecillion IP addresses, and 3GPP LTE and its further enhancements provides impressive high bitrates cost-efficiently. That been said, there is still a limit on the amount of data that can go through a frequency channel. Therefore, the surge in demand for data by the billions of devices emphasizes the need to re-visit spectrum planning. Beginning with a review on the success of unlicensed spectrum operations, this work looks into the potentials of complementing the licensed frequency bands with unlicensed by tapping into the advantages of millimeter wave access technology

Transition Techniques of the Future Internet Protocol-IPv6

In the 1970’s the Internet Protocol (IP) was designed after much decision on it. Thirty years after its deployment and usage, the resulting design (i.e., IPv4) has been more than sufficient even though certain techniques had to be implemented to further reduce the rapid depletion of the IPv4 address space due to the exponential growth of the internet. However, the techniques implemented to further reduce the rapid depletion of IPv4 were only just temporary and have serious limitations. It should no longer be news that the transition from IPv4 to the new internet protocol (IPv6) will have to happen now. The transition techniques to achieve this transition process and the benefits that will accrue from having such an addressing scheme are the ultimate objective of this work. The paper clearly iterated that for successful transition to take place, organizations must first begin to run IPv4 and IPv6 in parallel. The vulnerable impacts of the transition and the appropriate solutions were explained