Review of error detection of data link layer in computer network

Afiqah Azahari, Raed Alsaqour, Mueen Uddin and Mohammed Al-Hubaishi

Error control describes how the network handles and detects errors especially in the data link layer. In this paper, we present on an overview of error control regarding error detection and error correction. Error control happens in data link layer. We mainly discuss the type of error detection mechanisms that is used to detect the errors and how the errors will be corrected so the receiver can extract the real data. At the end of this paper, the conclusion and the future work are presented.

Evaluation of equilibrium moisture content in ligno-cellulosic residues of olive culture

Antonio Messineo, Giuseppina Ciulla, Simona Messineo, Maurizio Volpe and Roberto Volpe

The use of ligno-cellulosic residuals from agriculture as means for renewable energy production is well known; nonetheless significant problems still exist on development of bioenergy value chains. Moisture content and hygroscopicity are among these problems. Higher moisture content of the biomass means lower calorific value and higher perishability, hence storage difficulties. For this reason it is important to evaluate how the moisture content of the material varies while it is stored and how the calorific value of the feedstock is affected by it. The purpose of this study is to determine the variation of moisture content and its influence on lower calorific value (LCV) of four types of solid residual biomass: oven dried chipped olive tree trimmings, milled olive pomace; oven dried olive tree trimmings and fresh olive tree trimmings. Moisture content of the samples is calculated by means of thermogravimetric analysis (TGA) according to standard CEN/TS 14774-2:2004, while the LCVs are calculated by means of a calorimeter, following standard UNI EN 14918:2010. All the biomass samples were left to reach equilibrium moisture content (EMC) in a temperature and humidity controlled environment. Two different phases were analyzed with respect to moisture uptake rates: 1) fast moisture uptake rate phase (first four hours of exposure) and 2) slow moisture uptake rate, (the days following the first four hours of exposure). Samples experiencing fast moisture uptake rate, during the first four hours of exposure, were kept in a monitored ambient at T=22 ± 1 °C and RH=59 ± 2%, while samples exposed to slow moisture uptake rate were kept in a climatic chamber at three different set of temperature and humidity controlled environment simulating the climatic conditions in different periods of the year in Enna province: 10°C - 80% RH (winter), 15°C - 70% RH (spring/autumn) and 20°C - 55% RH, (summer). The results obtained show that the olive pruning chips (0.425 mm to 1.00 mm and 1.00 mm to 2.00 mm particle size ranges) stored in a heap  in a controlled climatic chamber require approximately 20 days to reach EMC. Depending on the particle size range EMCs  reach the values of  6.2 and 7.5% by weight in the "summer" condition, 14.3% and 16.9% in "spring/autumn" condition, 24.1% and 28.2% in "winter" condition. Moisture is absorbed gradually over time and results show that in the first four hours, the dry sample exposed to ambient condition (T=22 ± 1 °C and RH=59 ± 2%) reach a moisture content between 0.75 and 0.96% of its weight; the LCV at equilibrium is evaluated between 18, 576 J•odg-1 and 18, 793 J•odg-1, the higher value related to the bigger particle size range examined. Pomace heap under the same experimental set up and time period, reaches an equilibrium moisture content of 8.5% and 9.7% (summer conditions), 19.2% and 22.0% (spring/autumn condition) and between 30.9% and 34.1% (winter condition). Olive pomace accumulates moisture relatively faster than olive trimmings as dry sample recovers about 1.61% to 1.97% of moisture in the first four hours of exposure. The LCV at equilibrium is determined between 20, 145 J•odg-1 and 20, 436 J•odg-1. Pruning dried samples reach an EMC equal to 6.1% in approximately 25 days, with a LCV equal to18, 921 J•odg-1 ± 1.9%. Heaps of fresh prunings reach an EMC of 8.2% in approximately 20 days; LCV of the feedstock is 19, 356 J•odg-1± 1.6%.

The performance of two antenna design shapes in ultra-wideband wireless applications

Rashid A. Fayadh, Fareq Malek, Hilal A. Fadhil, and Jaafar A. Aldhaibani

The extensive requirements for small Ultra wideband (UWB) communication systems lead to design active and small size antennas. In this research two rectangular microstrip antennas were designed to cover the UWB operating frequency of 7.5 GHz starting from 3.1 GHz up to 10.6 GHz. The simulation and prototype designs are presented in this paper using CST microwave studio software tools and printed circuit board, respectively. The designs satisfy the requirements of UWB technology and according to the geometrical shape, one is called prong-shape patch antenna and the other is rake-shape patch antenna. The simulated results for return loss (S11) and radiation pattern have been demonstrated that the antenna designs are suitable for UWB communication systems. The measured results for same parameters were concluded by network analyzer and anechoic chamber to reinforce the performance of these antennas in wireless UWB applications. After confirming the performance of these designs, the comparison was done between the two to see the advantages in use.

Porosity estimation of carbonate rocks with multispec processing technique

N. D. Nurgalieva and N.G. Nurgalieva

Porosity is known as one of the main properties of reservoir rocks. The exact value of this parameter is difficult to measure. In present paper it is proposed using MultiSpec processing technique as cost-effective alternative method for estimating 2D-porosity from thin sections images of carbonate rocks on base of core samples picked out from carbonate reservoir rocks of Tournasian age in well, situated on southern slope of South-Tatarian Arch (Volga-Ural region, Russia).

Viscoelastic surfactants application in hydraulic fracturing, it’s set back and mitigation - an overview

Aliu Abdulmumin Omeiza and Ariffin Bin Samsuri

Abstract:

Fracturing fluid is an essential component of hydraulic fracturing stimulation. The oil and gas industry has experienced transformation in fluid technology for hydraulic fracturing. Fracturing fluid should have the reasonable viscosity that can suspend and transport proppants into the fracture. It should also be able to keep the fracture open throughout the life of the well. Sometimes ago polymers were used for this purpose as it’s able to withstand high temperature under well condition. However due to formation of filtercake caused by the polymer based fluids, there are formation and  conductivity damages done to the formation, therefore its application in fracking a bit limited. Viscoelastic surfactant (VES) were then applied in fracturing operation as they exhibit viscous and elastic behaviour in brine (increased viscosity) by entanglement of the VES micelles. But the problem with this fluid is that, its viscosity is drastically reduced at high temperature. Additions of inorganic or organic nanoparticles have been found to help in stabilizing the viscosity of this VES fluid at very harsh condition of high temperature and pressure. Internal breakers are also added to the VES fluid to help break the fluid into low viscosity fluid after fracturing has been done so as to enhance easy flowback (cleanup) of the VES to the surface. This paper however highlights the process of VES fluid application in hydraulic fracturing stimulation, its set back and mitigation approach adopted in the industry using nanoparticles to stabilize its viscosity at high temperature.

Aircraft diesel engines controlled by fuzzy logic

Luca Piancastelli, Leonardo Frizziero and Eugenio Pezzuti

Abstract:

Normally in diesel and gasoline engines, common rail systems are employed. The key factors for correct engine power management are pressure, precision and velocity. Digital computers and PID control systems characterize current systems. Recovery strategies are used when anomalies occur and engine performance is significantly reduced. So, restoring normal conditions needs technical assistance. For safety reasons this approach cannot be used in aeronautical, naval and energy-supply applications. In some cases it is necessary to utilize all the possible energy from the power unit causing significant life-reduction of the engine. In this case a progressive reduction strategy should be used and injection law should be reduced accordingly. For this purpose injection control based on fuzzy logic is more effective. In this case, traditional PID control systems are substituted by fuzzy logic control. A reference map is introduced in the Full Authority Digital Electronic Control; this map is interpreted by the fuzzy logic control system that adapts the injection law to the current engine situation. This method has been experimented on a common-rail test bed and results are compared with traditional “binary recovery strategy” FADEC.

Reviews on avalanche photodiode for optical communication technology

Mohd Azlishah Othman, Siti Nabilah Taib, Mohd Nor Husain and Zul Atfyi Fauzan Mohammed Napiah

This paper presents a review of avalanche photodiode in optical communication technology. Avalanche photodiode is one of photodiodes can be operated in high electric field in order to achieve high bit rate optical fiber communication systems. In long distance optical communication, the avalanche photodiode (APDs) is frequently the photo detector of choice owing to its internal gain, which provides a sensitivity margin relative to PIN photodiode. Previously, studies and research has improved the performance of APDs in optical communication systems, the research include development and improvement in terms of materials used in device structures of avalanche photodiodes. A review of Avalanche photodiode and the principle of avalanche photodiode work, as semiconductor will be discussed. This reverse bias device also used guard ring as is to remove the high electric fields and to drain the surface currents due to high reverse bias voltage. It also showed the mode of operation used in avalanche photodiode and potential materials that can be used optimum in looking for best avalanche photodiode. In last section, this paper reviews about future works in the research of avalanche photodiode.

Abstract:

City bus, namely busway was being popular in Jakarta. In several busway fleets, there are sliding doors that have large dimension that can inhibit the mobility of passenger. However, a new model of this door has been redesigned. The dimension of new design was the same as the dimension of the existing system i.e., 1800 mm height x 900 mm width but using square pipe 50 x 25 mm instead of using 60 x 30 mm square pipe as door frame. The strength of the new model was tested using Finite Element Method and showed that new door was strong enough to withstand the load. However, the strength should be investigated further experimentally. In this research, the experimental investigation of the strength of new sliding doors model were discusses. The model of the door was made from structural steel with minimal yield strength 175 MPa. The model was placed horizontally and supported in each corner of the door. A mass of 50 kg were loaded in the middle of the door. Three elements rosette strain gage were used as transducer and located in the critical point of the door. The strains were recorded using precision data Logger and von Misses stress was calculated. The result showed that the new design was strong enough to withstand the load.

Abstract:

Bibolo (Lova trichilioides) wood is market locally under a commercial name of Dibetou and in what follows it shall be referred to as bibolo. Stress induced changes in intrinsic timescale were investigated by nonlinear short period (3 h) creep tests on bibolo at room temperature and atmospheric pressure, for streses ranging from 9.19 MPa to 27.56 Mpa. The creep strain and creep compliance curves versus time at four different stress levels were determined. The resultant creep compliance curves depart from each other, indicating nonlinear viscoelastic behaviour. The creep strain curves were shifted along the logarithmic time axis to get a master creep curve at a given reference stress level according to the principle of time-stress superposition. It is shown that the time-stress superposition principle provides an accelerated test method for evaluating the long-term mechanical performance this wood.

Numerical assessment of material mismatch effect over mode I crack tip zones in glare

Abstract:

The nature and the size of Mode I crack tip zones developing in cracked fibre metal laminate, Glare, (Aerospace aluminum alloy layers + fibre and resin based prepregs) when subjected to far field load differ from those in similarly loaded cracked plain aerospace aluminum alloy specimen due to amplification or reduction in crack tip stress field of the laminate that is caused by load transfer effect due to property mismatch between un-identical materials in the laminate. This difference is assessed by finite element method in the paper. Glare laminates with two types of Mode I crack orientations are investigated - Type I in which the Mode I crack in outer aluminum layer is normal and near to the prepregs and Type II in which the Mode I cracks run across the aluminum layers in presence of delaminations at aluminum-fibre interfaces. Two different laminate curing temperatures of 90 deg. C and 120 deg. C are separately considered in the analysis to estimate the influence of residual stress over crack tip characteristics. Monotonic tensile stress of 150 MPa is applied over the laminates. Identically, cracked and stressed, plain aerospace aluminum alloy specimens are also modeled for the purpose of comparison. The intensity of stress fields near Mode I crack tips in the laminates is observed to be different than that near crack tips in plain aluminum specimens - amplified in Type I and diminished in Type II laminates. Consequently, the size and the shape of crack tip zones in laminates vary from those in plain aluminum specimens. Values of J integrals near crack tips are also found to be more and less than the induced J values in Type I and Type II laminates respectively that support the amplification and shielding effects at the crack tips in the laminates.

Use of HFC fluids as suitable replacements in low-temperature refrigeration plants

Antonino La Rocca, Vincenzo La Rocca, Antonio Messineo and Domenico Panno

An experimental investigation of the performance of a low-temperature refrigerating unit working with R22 and a comparison of its performance when operating with replacement HFC fluids in accordance with the European Regulation CE-1005/2009 are presented in this paper. Plant working efficiency was tested with R22, as baseline, and then compared with four different HFC fluids: R413A, R417A, R422A and R422D. The refrigerating unit was a vapour-compression plant equipped with a reciprocating double-cylinder compressor able to keep the cold room at -20ºC. Lower values of the temperature at the end of compression and polytrophic exponent can be achieved with the HFC tested. Substituting the R22 led to refrigerating plant to underperform. The COP was lower for all the replacement fluids showing inferior energy efficiency and higher energy consumption. The TEWI parameter was also evaluated and compared for all the fluids tested in the present investigation, suggesting TEWI increments substituting the original fluid.

The assessment of Small Hydro Power (SHP) sites for project planning and development represents a relatively high proportion of overall cost. A high level of experience and expertise is required to accurately conduct this multi-dimensional assessment at both pre-feasibility and feasibility analysis stage. A variety of multi-criteria decision analysis or making (MCDA or MCDM) methods as well as computer-based feasibility assessment tools have been developed for the same. However, a reliable assessment implies physical site surveying and planning at pre-feasibility stage itself. The advent of Geographic Information System (GIS) along with these feasibility analysis software tools has been of enormous use for the feasibility analysis of SHP project at minimum time-cost-effort for making further decision. To the best of the author’s knowledge this software tool based novel approach for Indian small hydropower project feasibility analysis is absent in renewable energy literatures due to its assessment complexity.