Adaptive spatial mode of space-time and spacefrequency OFDM system over fading channels

In this paper we present a 2 transmit 1 receive (1 Tx : 1 Rx) adaptive spatial mode (ASM) of space-time (ST) and space-frequency (SF) orthogonal frequency division multiplexing (OFDM). At low signal to noise ratio (SNR) we employ ST-OFDM and switch to SF-OFDM at a certain SNR threshold. We determine this threshold from the intersection of individual performance curves. Results show a gain of 9 dB (at a bit error rate of 10-3) is achieved by employing adaptive spatial mode compared to a fixed ST-OFDM, almost 6 dB to fixed SF-OFDM, 4 dB to Coded ST-OFDM and 2 dB to a fixed coded SF-OFDM, at a delay spread of 700 ns

Sensor Fusion Algorithm by Complementary Filter for Attitude Estimation of Quadrotor with Low-Cost IMU

This paper proposes a sensor fusion algorithm by complementary filter technique for attitude estimation of quadrotor UAV using low-cost MEMS IMU. Angular rate from gyroscope tend to drift over a time while accelerometer data is commonly effected with environmental noise. Therefore, high frequency gyroscope signal and low frequency accelerometer signal is fused using complementary filter algorithm. The complementary filter scaling factor K1=0.98 and K2=0.02 are used to merge both gyro and accelerometer. The results show that the smooth roll, pitch and yaw attitude angle can be obtained from the low cost IMU by using proposed sensor fusion algorithm

Sliding mode control for altitude and attitude stabilization of quadrotor UAV with external disturbance

This paper addresses the problem of robust altitude and attitude control of ‘×’ mode configuration quadrotor UAV using Lyapunov stability based sliding mode control with saturation function. The dynamic model of the quadrotor was derived by considering nonlinearity factor. MATLAB Simulink was used to simulate the model in two different conditions; without and with the presence of external disturbance. This was done to test the robustness of the control method. Simulation results showed that the sliding mode controller provides good performance and robustness against disturbance

Sonographic Appearance of Abdominal Wall at the Left Flank of Laparotomy Incision Site in Ettawah Grade Does

The aim of this study was to describe the sonographic appearance of abdominal wall at the left flank of laparotomy incision site in 11 mated Ettawah grade does. Brightness-mode ultrasound examination by using transducer with frequency of 5.0-6.0 MHz was conducted to grouping the does based on their pregnancy statuses. The incision site of the abdominal wall at left flank laparotomy was transcutaneous-scanned as long as 8 cm vertically. The sonographic appearance of the laparotomy wall thickness showed that in all groups of does were similar and not different statistically. The thickness of oblique external and oblique internal abdominal muscles increased in the pregnant does as compared to non-pregnant does (P<0.05)

Evaluating the Impact of Transmission Range on the Performance of VANET

Recently, interest in the field of Vehicular Ad-hoc Networks (VANETs) has grown among research community to improve traffic safety and efficiency on the roads. Despite the many advantages, the transmission range in vehicular network remains one of the major challenges due to the unique characteristics of VANETs such as various communication environments, highly dynamic topology, high node mobility and traffic density. The network would suffer from a broadcast-storm in high vehicular density when a fixed transmission range in VANET is used, while in sparse vehicular density the network could be disconnected frequently. In this paper, we evaluated the impact of different transmission ranges and number of flows formed between vehicles in a highway scenario using AODV as routing protocol. In order to validate the simulation of VANET, traffic and network simulators (SUMO & NS-2) have been used. The performance was evaluated in terms of packet delivery ratio and end-to-end delay. The simulation results have shown that better performance was achieved in term of higher PDR and lower end-to-end delay for less than 500 meters transmission range. On the contrary, the PDR started to decrease and end-to-end delay increased when the transmission range exceeded 500 meters. The performance degraded as the number of flows increased

Bomb blast injuries: tertiary care hospital in-patient experience over the last 20 years

Abstract OBJECTIVE: To examine the distribution and nature of limb injuries in young bomb blast victimsand their management in a tertiary healthcare setting. METHODS: The retrospective study was conducted at the Aga Khan University Hospital, Karachi and data was searched using the University Medical Record Database with International Classification of Diseases-Ninth Revision-Clinical Modification codes for injuries and terrorism between 1990 and 2012. Data regarding injuries, including admission time, hospital stay duration, interventions and mortality, was collected and classified as per the New Injury Severity Score. RESULTS: There were 22 patients in the study; 19(86.3%) males and 3(13.7%) females. The mean age of the sample was 13.1±4.1 years. Median length of hospital stay was 9 days (range: 2-42 days). Sixteen (72.7%) patients required operative intervention. Patients rarely had accompanying injuries with limb injuries. Four (18%) patients needed open reduction and internal fixation. Two (9%) patients needed open reduction and external fixation. One (4.5%) patient required a limb amputation. One (4.5%) patient required ileal resection with ileoileal anastomosis due to shrapnel perforations. There was no mortality. CONCLUSIONS: The young age group was not severely affected by limb trauma. Injuries sustained were infrequently accompanied by severe/critical injury severity scores

Primary total hip arthroplasty: Staying out of trouble intraoperatively

Total hip Arthroplasty is one of the most successful and commonly performed procedures in Orthopaedic Surgery. Meticulous preoperative planning allows to surgeon anticipate potential problems to reduce postoperative complications and optimize patient outcomes. Currently, the posterior approach is the most common approach utilized in the United States. In order to prevent errors in stem version, especially with cementless fixation, the entry point should be posterior, and the initial entry point should be aligned in the correct anteversion as this will determine the ultimate version of the stem. Preoperative evaluation should asses for true and apparent lengths. For successful osseointegration of cementless components, bone ingrowth occurs when there is less than 40 μm of motion between the implant and bone. Certain socket conformations such as elliptical versus hemispherical are more prone to generate fractures at the time of impaction

PI Controller Design Using Model Reference Adaptive Control Approaches For A Chemical Process

This paper discusses the application of Model Reference Adaptive Control (MRAC) concepts in designing an adaptive feedback controller to tune a given PI controller. The approaches of using the gradient (MIT) and stability (Lyapunov) methods are shown. The effectiveness of the two methods are shown through simulation and comparison is made to show which method give the best result. The results show that the stability method produces a better result

Coverage degree in mobile nodes wireless sensor network

Coverage degree and mobility have acquired a lot of attention lately in Wireless Sensor Network (WSN). This paper shows that nodes mobility can enhance coverage degree for WSN. Analytical model is introduced to describe the coverage degree in mobile nodes wireless sensor network. MATLAB was used to build the simulator. The analytical work is validated by simulated results. Both of analytical model and simulation showing that the coverage degree has been enhanced in Mobile Nodes Wireless Sensor Network (MNWSN) as compared to static network

Temperature influence on total volatile compounds (TVOCs) inside the car cabin of visible light transmittance

In the automotive industry indoor air quality or Vehicle Indoor Air Quality (VIAQ) are caused by various substances emitted from interior materials inside a vehicle. The volatile organic compounds (VOCs) are an example of emitted substances from the interior materials which is harmful to the human body. As stated by previous researches, there is a strong correlation between the total VOCs emission and interior temperature. This occurs due to the solar radiation through the back window glasses, windscreen and side window glasses. This trapped heat can accelerate the melting process of trim materials such as hard plastic and rubber, thus causing the emission of total VOCs (TVOCs). Therefore, reducing the percentage of visible light transmittance (VLT) will help to reduce radiation process. The aim of this study is to investigate the effect of VLT level on TVOCs emission in the vehicle cabin under static condition (parked and unventilated) and operating condition (driving and air-conditioned). For static condition the result shows that the TVOCs concentration linearly decreases whenever the percentage of VLT level decreases. However, for operating condition the percentage of VLT have less significance after 50 minutes driving time. In conclusion, the VLT levels have a strong relationship to the TVOCs concentration despite after a long driving time