RF Front End Receiver for WiMAX Application

This paper presents the design of a high gain, low noise direct conversion Radio frequency(RF) front-end receiver system. The Front end receiver is designed to operate at 5.8 GHz compliant with IEEE 802.16 WIiMAX standard. The system consists of a low noise amplifier (LNA), a radio frequency amplifier (RFA), a power divider and two band pass filters. The overall performance of the RF front-end receiver system produced a gain of 52.4 dB. A cascaded LNA designed for the system produced a high gain of 36.8 dB. The RFA contributed an extra gain 15.6dB. The overall noise figure achieved for the system is 3.7 dB. The return loss achieved is -25.5 dB for the RFA. The radio frequency bandwidth recorded for the system is above 1120 MHz. The measured power divider insertion loss is 2.80 dB. Using microstrip technology for designing the Chebyshev filter, the insertion loss is 3.00 dB and the channel bandwidth recorded is 107 MHz which can accommodate 4 sub channels IEEE WiMAX standard

What's Up Omni? The Relationship Between Omni-Channel Supply Chain and Logistics Service Quality In Influencing Online Purchasing Behaviour

Consumer behavior had been affected by the evolution of digital technologies and the internet. Online shopping is becoming more popular, with e-commerce market growth that encourages the involvement of retailers. However, consumers' satisfaction is still the same as they request for a seamless and frictionless shopping experience, an 'Omni-channel supply chain.' Retailers need to understand the new phenomenon and how the concept is influencing customer purchasing behavior, especially online shopping. Several types of research had highlighted the importance of logistics service quality in predicting online purchasing behavior. Thus, this study investigates the relationship between the Omni-channel supply chain and logistics service quality in influencing online purchasing behavior. A survey-based approach is used to collect data from consumers about their perceptions. Overall, the study had enhanced the understanding of the relationship between the Omni-channel supply chain and logistics service quality with online purchasing behavior. Besides, the knowledge of online purchasing behavior in the Omni-channel context has enabled a retailer to allocate resources in designing new strategies. 

Serological prevalence and haematological profile of Feline Immunodeficiency virus (FIV) in semi-roamer and outdoor cats

Feline Immunodeficiency virus (FIV) is among the most common infectious diseases diagnosed in cats. In this study, 55 client-owned cats presented to the University Veterinary Hospital, Universiti Putra Malaysia (UVH-UPM) were sampled. Inclusion criteria were semi-roamer and outdoor cats aged more than 6 mont hs old. Blood samples were collected for serological testing us ing commercial immunochromatographic test kits and haematological an alysis. Of the 55 cats tested, 13 cats (23.6%) tested positive for FIV antibodies. There was a significant association (P<0.05) between neuter and health status to FIV seropositivity. FIV infect ions were more likely occured in intact cats compared to neutered cat s, and in sick cats compared to healthy cats. Erythrocytes, hemoglobin and packed cell volume (PCV) were significantly redu ced (P<0.05) in FIV cats compared to FIV-seronegative cats, however these parameters were within the normal range

Stall margin improvement in a low-speed axial compressor rotor using a blockage-optimised single circumferential casing groove

The stall margin of tip-critical axial compressors can be improved by using circumferential casing grooves. From previous studies, in the literature, the stall margin improvement due to the casing grooves can be attributed to the reduction of the near casing blockage. The pressure rise across the compressor as the compressor is throttled intensifies the tip leakage flow. This results in a stronger tip leakage vortex that is thought to be the main source of the blockage. In this paper, the near casing blockage due to the tip region aerodynamics in a low-speed axial compressor rotor is numerically studied and quantified using a mass flow-based blockage parameter. The peak blockage location at the last stable operating point for a rotor with smooth casing is found to be at about 10% of the tip chord aft of the tip leading edge. Based on this information, an optimised single casing groove design that minimises the peak blockage is found using a surrogate-based optimisation approach. The implementation of the optimised groove is shown to produce a stall margin improvement of about 5%

Single and multiple circumferential casing groove for stall margin improvement in a transonic axial compressor

The stability limit of a tip-stalling axial compressor is sensitive to the magnitude of the near casing blockage. In transonic compressors, the presence of the passage shock could be a major cause for the blockage. Identification and elimination of this blockage could be key to improving the stability limit of the compressor. In this paper, using numerical simulation, the near casing blockage within the transonic rotor, NASA Rotor 37, is quantified using a blockage parameter. For a smooth casing, the blockage at conditions near stall has been found to be maximum at about 20% of the tip axial chord downstream of the tip leading edge. This maximum blockage location is found to be consistent with the location of the passage shock-tip leakage vortex interaction. A datum single casing groove design that minimises the peak blockage is found through an optimisation approach. The stall margin improvement of the datum casing groove is about 0.6% with negligible efficiency penalty. Furthermore, the location of the casing groove is varied upstream and downstream of the datum location. It is shown that the stability limit of the compressor is best improved when the blockage is reduced upstream of the peak blockage location. The paper also discusses the prospects of a multi-groove casing configuration

Optimized non-linear multivariable grey model for carbon dioxide emissions in Malaysia

This paper analyses the relationship between carbon dioxide emissions with the energy consumption from the year 2005 to 2014 in Malaysia by introducing an optimized non-linear multivariable grey, NGM(1,N) model by establishing a power exponent term for its subsequent relevant factors. The aim of this research is to improve the existing NGM(1,N) model by solving the effect of non-linear properties which is able to correlate among the consequent factors based on the selection of power exponent optimization. This paper will also introduce the transformed NGM(1,N) known as TNGM(1,N) model that produces a more accurate result compared to NGM(1,N) model that prompted simulated output. The power exponent term value was determined using the generalized reduced gradient (GRG) method in Microsoft Excel Solver. It is proven that the TNGM(1,N) model performs the best and hence it serves as vital information for the government's environmental-related agencies and policymakers to focus on the effort to promote green efficient technology to society at large by reducing the releases of carbon dioxide emissions to the environment