Distributed temperature measurements using optical fibre technology in an underground mine environment

This article experimentally examines the applicability of a temperature measuring and monitoring system using distributed temperature sensing by means of an optical fibre in an underground mine environment. The temperature distribution along an optical fibre can be detected by measuring the Raman backscattering of the stokes and anti-stokes lines. The distributed temperature sensing system provided valuable information for the mine safety control and the mine ventilation system. In addition, it proved to be capable of measuring air temperature in the entire mine with an accuracy of 1 °C and within the distance resolution of 1 m. The heating and cooling processes could be detected and the rate of heat generation at any location of the mine could be accurately determined from the temperature measurements. This technology has the potential to be linked to other measuring devices of an underground mine environment in order to develop a safer ventilation control system.     

A Survey of VLSI Implementations of Tree Search Algorithms for MIMO Detection

Multiple-input multiple-output (MIMO) detection algorithms have received considerable research interest in recent years, as a result of the increasing need for high data-rate communications. Detection techniques range from the low-complexity linear detectors to the maximum likelihood detector, which scales exponentially with the number of transmit antennas. In between these two extremes are the tree search (TS) algorithms, such as the popular sphere decoder, which have emerged as attractive choices for implementing MIMO detection, due to their excellent performance-complexity trade-offs. In this paper, we survey some of the state-of-the-art VLSI implementations of TS algorithms and compare their results using various metrics such as the throughput and power consumption. We also present notable contributions that have been made in the last three decades in implementing TS algorithms for MIMO detection, especially with respect to achieving low-complexity, high-throughput designs. Finally, a number of design considerations and trade-offs for implementing MIMO detectors in hardware are presented.     

Pile-clayey soil interaction analysis by boundary element method

This paper is an attempt to solve the soil-pile interaction problems using the boundary element method(BEM).A computer package called PGroupN,which deals mainly with the analysis of the pile group problem,is employed in this study.Parametric studies are carried out to assess the impacts of the pile diameter,pile length,ratio of spacing to diameter and the thickness of soil stratum.The external load is applied incrementally and,at each increment,a check is made that the stress state at the pile-soil interfaces does not violate the yield criteria.This is achieved by specifying the limited stresses of the soil for the axial pile shaft capacity and end-bearing resistance.The elements of the pile-soil interface yielded can take no additional load,and any increase in load is therefore redistributed between the remaining elements until all elements have failed.Thus,by successive application of loading increments,the entire load-displacement relationship for the pile group is determined.It is found that as the applied load reaches the ultimate bearing capacity of the pile group,all the piles will share the same amount of load.An exception to this case is for the center pile in a group of 9 piles embedded in clay,which is not consistent with the behaviors of the other piles in the group even if the load reaches the ultimate state.For the 4 piles group embedded in clay,the maximum load carried by the base does not exceed 8% of the load carried by each pile with different diameters.This low percentage ascertains that the piles embedded in cohesive soils carry most of the load throughout their shafts.     

Job Behavior of Construction Project Managers: Determinants and Assessment

The paper reports the findings of an investigation into the psychosocial aspects of the work of construction project managers (PMs) in the United Kingdom. A theoretical model, which identified the different variables that may influence the behavior and effectiveness of PMs was developed. This study has used an adapted form of the behaviorally anchored rating scales (BARS) to measure a PM's effectiveness. The technique yielded five behavioral dimensions by which a PM's role may be described, and it was used in a survey involving 62 PMs. Analysis of the data suggests that a PM's effectiveness was influenced by situational and personal variables. The results strongly suggest that by understanding the complexity of such relationships, construction firms can influence the direction and behavior of PMs. The results also suggest that the behavior of PMs and project performance varied independently.     

Power system design and in orbit performance of Algeria's first micro satellite Alsat-1

On the 28th November 2002, Algeria's first enhanced micro satellite was launched into a 686 km low earth orbit onboard a Cosmos 3M rocket from Plesetsk. The spacecraft was designed, manufactured and launched as a technology transfer programme between the National Centre of Space Techniques (CNTS) Algeria and Surrey Satellite Technology Limited (SSTL) United Kingdom in the timescale of 18 months.     

Histochemical analysis of bandage contact lens precipitates.

Contact lens deposits have been reported previously with extended wear of soft contact lenses, with proteins, lipids, mucous, and various salts such as chloride, potassium and calcium being deposited on the lens surface [1]. We report an unusual case of precipitates on the surface of a bandage contact lens (BCL) following intensive treatment with topical preservative free artificial tears. Evaluation included microscopic and histochemical analysis of the BCL. We have also reviewed the literature for previous reports of contact lens precipitates.     

Analysis of implementing phase change materials in open-air swimming pools

Open-air swimming pools in Mediterranean climate regions are heated by direct solar radiation with no auxiliary heating systems. In order to extend the swimming season or improve comfort conditions, solar collectors or pool coverings may be used. In this paper, another approach was followed through the use of phase change materials (PCM). Two methods of introducing the PCM were considered: (1) encapsulated in the sidewalls and bottom of the pool, and (2) use the PCM in an external heat exchanger. Heat is stored when water temperature is sufficiently high, while it is released when water temperature drops below comfort levels. A numerical model was built and validated for predicting the evolution of the water temperature, by taking into account meteorological data at three different locations in north-east of Spain. The simulations showed that using phase change materials provided some improvement of water conditions, especially when used in an external heat exchanger.     

Heat transfer enhancement of nanofluids flow in microtube with constant heat flux

In this paper, laminar convective heat transfer in a two-dimensional microtube (MT) with 50 μm diameter and 250 μm length with constant heat flux is numerically investigated. The governing (continuity, momentum and energy) equations were solved using the finite volume method (FVM) with the aid of SIMPLE algorithm. Different types of nanofluids Al₂O₃, CuO, SiO₂ and ZnO, with different nanoparticle size 25, 45, 65 and 80 nm, and different volume fractions ranged from 1% to 4% using ethylene glycol as a base fluid were used. This investigation covers Reynolds number in the range of 10 to 1500. The results have shown that SiO₂–EG nanofluid has the highest Nusselt number, followed by ZnO–EG, CuO–EG, Al₂O₃–EG, and lastly pure EG. The Nusselt number for all cases increases with the volume fraction but it decreases with the rise in the diameter of nanoparticles. In all configurations, the Nusselt number increases with Reynolds number.     

SUPPLY AND DEMAND OF LIGHT NAPHTHA AS POTENTIAL PETROCHEMICAL FEEDSTOCK IN SAUDI ARABIA

ABSTRACT

Saudi Arabia is a major crude oil producer and exporter. Additionally, with the completion of its master gas gathering and treatment system petrochemical industries became the Kingdom's second major industrial sector. Currently, the Saudi petrochemical industry depends mainly on (C₁) methane and (C₂) ethane components of associated gas (AG) and natural gas (NG) as feedstocks. A variety of basic petrochemicals are now being produced principally by plants of the Saudi Basic Industries Corporation (SABIC).

There is a necessity of enhancing the use of various under-utilized hydrocarbon resources. At present, one of the favored under-utilized resources and potential candidates for upgrading is light naphtha (LN). Because LN has the advantage of producing a more diverse petrochemical product portfolio than C₁ and C₂ components, it is expected that LN will assume an increasing importance as feedstock in the future development of petrochemical industries in Saudi Arabia. However, industrial opportunities for economies of large-scale production of petrochemicals based on LN might not be favored.

Saudi Arabia's chemical and petrochemical industrial sector has not yet been fully developed, and its production lines are not enough diversified to benefit from LN. The development and expansion of Saudi petrochemical industries usually follows the international trend in this sector, and benefits from its technological achievements. Worldwide global shift in the use of feedstock in this industrial sector will be reflected in the Saudi petrochemical industries. As the world trend is to maximize the utilization of under-utilized petroleum resources, one would expect optimization of LN utilization in Saudi Arabia in the near future.