Risk invoked self-scheduling of a Genco in the day-ahead energy market

P. Somasundaram and M. Ramesh Babu

This paper proposes a novel Cauchy mutated Memetic Particle Swarm Optimization (CMPSO) algorithm to solve the risk based self-scheduling problem of price taking Genco in a day-ahead energy market. In self-scheduling problem, certain risk is invoked due to uncertainty in forecasted electricity prices and fuel prices. The risk in the self-scheduling problem is modeled based on the portfolio selection. The risks in the energy prices are taken into account by using the covariance information of the available data. The Risk Invoked Self-Scheduling (RISS) is formulated as a mixed integer non-linear optimization problem and solved by using the proposed CMPSO. The effectiveness of the proposed CMPSO algorithm is demonstrated with two test systems.

Experimental evaluation of different fillers in dental composites in terms of mechanical properties

The aim of this study was to evaluate in vitro the influence of nano-sized filler particles and agglomerates of nano particles (nano cluster) in resin based dental composite material. Four commercially available resins based dental composites-Filtek Z250, Filtek Supreme, Filtek Z100 (3M ESPE, St Paul, MN, USA), Heliomolor (Ivoclar Vivadent, Schaon, Liechtenstein) containing different filler particle type and morphologies were investigated. The compressive strength, compressive modulus, flexural modulus and flexural strength of these composites were evaluated.

Study and analysis of a rectangular single slot microstrip antenna

Ali Abdulrahman Dheyab

This paper focuses the study and analysis of a rectangular  single slot patch antenna with a probe feed. The analysis is simulated with microwave office 2004 software package. This method is employed for analysis at the frequency band of 1 GHz to 3 GHz. It gave a good VSWR less than (2), return losses (RL) less than (- 10 dB) and impedance bandwidth of the order of (15.416) at the frequency band of (2.29 -- 2.66) GHz of [2 - 3] GHz.

Digital implementation of PFC half bridge converter fed PMBLDC motor using microcontroller

C. Umayal, B. Janani and S. Rama Reddy

Digital Simulation and implementation of a Power Factor Correction (PFC) half bridge converter based adjustable speed voltage controlled VSI fed PMBLDC motor is presented in this paper. A single-phase AC-DC converter topology based on the half bridge converter is employed for PFC which ensures near unity power factor over wide speed range. The proposed speed control scheme has the concept of DC link voltage control proportional to the desired speed of the PMBLDC motor. The PFC converter based PMBLDCM drive is designed, modeled and simulated using MATLAB-SimuLink environment. This drive ensures high accuracy and robust operation from near zero to high speed. Simulation and experimental results of these systems are presented and the performance measures are compared. The simulation and experimental results with bridgeless boost converter show that there is an improvement in power factor.

Anaerobic digestion of cow dung for biogas production

Baba Shehu Umar Ibn Abubakar and Nasir Ismail

Abstract:

The effectiveness of cow dung for biogas production was investigated, using a laboratory scale 10L bioreactor working in batch and semi-continuous mode at 53^oC. Anaerobic digestion seemed feasible with an organic loading of up to 1.7 kg volatile solids (VS)/L d and an HRT of 10 days during the semi-continuous operation. The averaged cumulative biogas yield and methane content observed was 0.15 L/kg VS _added and 47 % respectively. The TS, VS and COD removals amounted to 49%, 47% and 48.5%, respectively. The results of the VS/TS ratio showed very small variation, which denote adequate mixing performance. However there was some evidence of ammonia inhibition probably due to the uncontrolled pH employed. The data obtained establish that cow dung is an effective feedstock for biogas production achieving high cumulative biogas yield with stable performance. The future work will be carried out to study the effect of varying organic loading rate on anaerobic digestion of cow dung in a semi-continuous mode.

Performance evaluation, emission characteristics and economic analysis of four non-edible straight vegetable oils on a single cylinder CI engine

Abstract:

An experimental investigation was carried out to analyze the performance and emission characteristics of a compression ignition engine fuelled with non-edible straight vegetable oils of Neem, Mahua, Linseed and Castor oil. Straight vegetable oils posed operational and durability problems when subjected to long term usage in CI engine. These problems are attributed to high viscosity, low volatility and polyunsaturated character of vegetable oils. Hence, process of transesterification is found to be effective method of reducing viscosity and eliminating operational and durability problems. Fuel preheating in the experiments for reducing viscosity of neat oils has also been done by a specially designed heat exchanger, which utilizes waste heat from exhaust gases. The test is conducted on single cylinder DI engine at constant speed of 1500 rpm. The performance parameters evaluated include thermal efficiency, brake specific fuel consumption (BSFC), brake specific energy consumption (BSEC), and exhaust gas temperature whereas exhaust emissions include mass emissions smoke. The results of the experiment in each case were compared with baseline data of diesel. Significant improvements have been observed in the performance parameters of the engine as well as exhaust emissions with use of neem, mahua and castor oil. Economic analysis was also done in the study and it is found that use of vegetable oil as diesel fuel substitutes has almost similar cost as that of mineral diesel.

Investigation of flow during intake stroke of a single cylinder internal combustion engine

C. Ramesh Kumar and G. Nagarajan

This paper deals with experimental investigation of swirling flow in the cylinder of a spark ignited engine. The variations in different non-dimensional parameters such as Flow Coefficient, Swirl Coefficient and Swirl Ratio at various valve lifts and throttle opening was studied using a steady flow bench. The swirl enhancement using valve shrouding, and twisted tape insert was also investigated. The results indicate that a higher swirl coefficient and swirl ratio can be achieved with shrouded valve and twisted tape with penalty on flow coefficient. These experimental results can be utilized to verify the results of modeling using commercial CFD codes and also for increasing the accuracy of mathematical modeling of combustion process in internal combustion engines.

Electrical resistivity imaging survey for shallow site investigation at University of Ibadan campus, south-western Nigeria

Oluwafemi Omowumi

Abstract:

A geo-electrical imaging survey was conducted at Abadina area of University of Ibadan, Ibadan, Southwestern Nigeria for shallow site investigation in order to determine the applicability of 2-D resistivity imaging in studying the weathered profile, which in turn determines how feasible the area would be in terms of erection of structures that will stand the test of time. The area is underlain mainly by augen gneiss with minor intrusion of dolerite dyke. Geophysical survey was carried out using 2-D electrical resistivity imaging technique. The Wenner array was employed. Field data were obtained for eight electrical imaging lines. The field data was subjected to inversion in order to remove geometrical effects from the pseudosection and produce an image of true depth and true formation resistivity. This layer has a range of resistivity from 10 to 100 Ohm-m. Partially weathered basement were observed on some of the traverses with relatively high resistivity anomalies. The image lines depict clearly that the subsurface material differs in terms of their competence. This is reflected in the weathering pattern where part of the image line was showing deeply weathered material towards one side whereas the other side is showing very shallow overburden at less than 2 m. In conclusion, site investigation using 2-D electrical resistivity imaging is an essential step to be taken before the erection of any structure for minimum damage because a balanced interaction of soil and structure is the hall-mark of a successful design of foundation. Further studies such as soil test should be carried out to ascertain the suitability of the soil for future planning of the site.

Is electro coagulation (EC) a solution to the treatment of wastewater and providing clean water for daily use

Daniel Ogwoka Siringi, Patrick Home, Joseph S. Chacha and Enno Koehn

Abstract:

Although electro coagulation is an evolving technology that is being effectively applied today for wastewater treatment, the paucity of scientific understanding of the complex chemical and physical processes involved is limiting future design and hindering progress. The objective of this review through a survey of the literature is to bring the chemistry and physical processes involved into perspective and to focus attention on those areas critically needing research.

Determination of cetane number of biodiesel and it’s influence on physical properties

P. Ravikumar and K. Sivaramakrishnan

Abstract:

Biodiesel, an alternative fuel can be used in diesel engine as neat or blended with diesel. The physio-chemical properties of fuel are important in design of fuel system for compression ignition engine run on diesel, biodiesel or biodiesel blends. Cetane number is an important parameter in evaluating the quality of biodiesel fuel. Its determination is usually arduous and expensive. The present study is aimed at developing the mathematical relationship between viscosity, density, calorific value, flash point and cetane number (CN). An equation was developed relating the cetane number and thermal properties. The predicted cetane number values are compared with the measured cetane number values. This work establishes the general dependence of cetane number on the thermal properties of biodiesel.

Effect of filler content on the mechanical properties of periwinkle shell reinforced CNSL resin composites

Michael Ikpi Ofem and Muneer Umar

Abstract:

Research into bio filler materials composite is gradually taking prominence due o its renewability. In this present work, three particle sizes (400μm, 600μm and 800μm) of milled periwinkle-shell (PWS) filled cashew nut shell liquid (CNSL) resin composites were developed by compression moulding technique with varying filler content (10 % to 40 % by weight). The developed PWS filled CNSL composites were then characterized by tensile, flexural and impact strength tests. The effect of filler content and particle size on the mechanical properties of the PWS filled CNSL composites was investigated. Results showed that, there was an improvement on the mechanical properties as the filler content increases while properties decreases as filler size increases. All properties tensile strength, flexural strength, % elongation, tensile modulus and impact strength slightly increased as the filler loading increases. While % elongation, tensile and flexural strengths decreases as particle sizes increases, tensile modulus and impact strength increases as particle sizes increases. The optimum properties were observed at 30 % filler content and 400μm.

Machinability of LM6/SiCp metal matrix composites with tungsten carbide cutting tool inserts

Rabindra Behera and G. Sutradhar

Abstract:

This paper explains the influence of machining parameters such as cutting forces and surface roughness on the machinability of LM6/ SiCp metal matrix composites at different weight fraction of SiCp. Machining tests were carried out at different cutting speed (i.e., 30, 68 and103 m/min) and different depth of cuts (i.e., 0.5, 1.0 and 1.5mm) at constant feed rate i.e., 0.05 mm/rev to study the machinability of  as cast composites.  It was observed that the depth of cut and the cutting speed at constant feed rate affects the surface roughness and the cutting forces during dry turning operation of cast MMCs. It was also observed that higher weight percentage of SiCp reinforcement imparts a higher surface roughness and needs high cutting forces. This experimental analysis and test results on the machinability of Al/SiC-MMC will provide essential guidelines to the manufacturers.

Operational characterization of a spray dryer for drying water, caustic soda and sodium chloride solutions

Olufemi B. A., Popoola G. O., Towobola O. R. and O. G. Awosanya

Abstract:

The spray drying of distilled water, 50 % w/w NaOH, 10 % w/w NaOH, and 25 % w/w NaCl solution was investigated. Operating conditions, dryer design and inherent properties of the liquids affected performance operational trends and degrees of dryness. The various phenomena observed indicated the difficulty in predicting the performance or suitability of any dryer for the purpose of drying a liquid without an investigative task. The maximum values of exit mass flow rate of dried liquid, dryer temperature, heat transfer coefficient, specific energy supplied and moisture content removed were 0.015 kgs^-1 for 25 % w/w NaCl solution, 402.6 K, 4.85 Wm^-2K^-1, 1, 941, 937.04 Jkg^-1 and 0.217 for distilled water respectively. The exit mass flow rates increases with specific energy supplied for all the liquids, except for 50 % w/w NaOH solution which decreases with specific energy supplied. The possibility of exploring, competing or improving quantitatively and qualitatively on the conventional mode of drying some of these liquids industrially seems promising, with the aim of overcoming their inherent and present challenges.

Effect of compression ratio on CI engine fueled with methyl ester of thevetia peruviana seed oil

M. K. Duraisamy, T. Balusamy and T. Senthilkumar

Abstract:

The high energy demand in the industrial world as well as in the domestic sector and pollution problems caused due to the widespread use of fossil fuels make it increasingly necessary to develop the renewable energy sources with lesser environmental impact than the conventional one. This has inspired curiosity in alternative sources for petroleum-based fuels. One possible alternative to fossil fuel is the use of oils of plant origin like vegetable oils/tree borne oils. A wide variety of tree borne oils and their suitability as alternate fuel had been investigated. In this paper, an attempt has been made to investigate the effect of compression ratio on performance and emission characteristics of 20% methyl ester of Thevetia Peruviana Seed Oil (TPSO) blended with 80% diesel (B20) when used as fuel in a diesel engine. Experiments were conducted in a Variable Compression Ratio (VCR) diesel engine with different compression ratios and base line experiment was also conducted with neat diesel operation at higher compression ratio for comparison. The various performance and emission parameters like., brake thermal efficiency, specific fuel consumption, the exhaust gas temperatures CO, CO₂, HC, NO_x, and smoke intensity were measured and analyzed. It was found that performance of the engine increased appreciably with less bsfc by increasing the compression ratio for biofuel blend. Also, it was observed that increase in compression ratio significantly reduced the CO, HC, NO_x and smoke emissions but with a slight increase in CO₂.

On the stability of a four species syn eco-system with commensal prey-predator pair with prey-predator pair of hosts-viii

B. Hari Prasad and N. Ch. Pattabhi Ramacharyulu

Abstract:

The present paper is devoted to an investigation on a Four Species (S₁, S₂, S₃, S₄) Syn Eco-System with Commensal Prey-Predator pair with Prey-Predator pair of Hosts (Host of S₁ washed out states). The System comprises of a Prey (S₁), a Predator (S₂) that survives upon S₁, two Hosts S₃ and S₄ for which S₁, S₂ are Commensal respectively i.e., S₃ and S₄ benefit S₁ and S₂ respectively, without getting effected either positively or adversely. Further S₃ is Prey for S₄ and S₄ is Predator for S₃. The pair (S₁, S₂) may be referred as 1^st level Prey-Predator and the pair (S₃, S₄) the 2^nd level Prey-Predator. The model equations of the system constitute a set of four first order non-linear ordinary differential coupled equations. In all, there are sixteen equilibrium points. Criteria for the asymptotic stability of four of these sixteen equilibrium points: Host of S₁ washed out states is established. The system would be stable if all the characteristic roots are negative, in case they are real, and have negative real parts, in case they are complex. The linearized equations for the perturbations over the equilibrium points are analyzed to establish the criteria for stability and the trajectories are illustrated.

Safety measures against man-in-the-middle attack in key exchange

C. Krishna Kumar, G. Jai Arul Jose and C. Sajeev

Abstract:

Several techniques have been proposed for the distribution of public keys. The ability to distribute cryptographic keys securely has been a challenge for centuries. The Diffie-Hellman key exchange protocol was the first practical solution to the key exchange dilemma. The Diffie-Hellman protocol allows two parties to exchange a secret key over unsecured communication channels without meeting in advance. The secret key can then be used in a symmetric encryption application, and the two parties can communicate securely. However, if the key exchange takes place in certain mathematical environments, the exchange becomes vulnerable to a specific man-in-the-middle attack, first observed by Vanstone [2]. We explore this man-in-the-middle attack, analyze countermeasures against the attack.

Enabling success factors and strategies for products of small entrepreneurs

B. S. Ravikiran and C. B. Vijaya Vittal

Abstract: