scholarly journals Efficiency Analysis on Small Sized Generators in Nigeria

2019 ◽  
Vol 2 (2) ◽  
pp. 37-44
Author(s):  
A. E. Airoboman ◽  
Mohammed A. S. Jibrin ◽  
J. O. Ademola ◽  
J. Oladokun ◽  
S. Ahmed ◽  
...  
Keyword(s):  
Power Factor ◽  
Experimental Analysis ◽  
Efficiency Analysis ◽  
Maximum Power ◽  
Experimental Results ◽  
Loading Conditions ◽  
Average Efficiency ◽  
Experimental Analyses ◽  
Potential Customers ◽  
Adequate Power

In this paper, efficiency analysis of small sized generators in Nigeria was considered. Experimental analyses were carried out on two (2) different samples of generators tagged “S” and “T” at different loading conditions (20%, 40%, 60% etc. of ratings) to ascertain the generators’ efficiencies as well as the maximum true power that could be drawn out from the generators. The experimental results are compared with the manufacturers ratings specified on the name plate of the generators. The results indicated an average efficiency of 44.9% and 55.7% for “T” and “S” respectively an indication that generator “S” is more efficient that “T”. The results also showed that the values of the power factor indicated on the generators are inaccurate as none of the generators could give the maximum power as indicated on their name plates based on the experimental analysis carried out. The generators selected were able to provide adequate power to the selected loads with efficiencies not up to 100% of the expected rated value of the generators. For generator “S” it was observed that the efficiency decreases from the highest rating to the lowest rating. Conclusively, this result suggests that portable generators dealers are taking advantage of the energy crises to importing generators not up to specifications to the Nigerian market at the expense of naïve customers. This paper recommends that proper standards and measures be put in place and enforced by the relevant authority for conformity of standards to all imported generators to save guard and protect the interest of potential customers and Nigerians.

THE THEORY OF SOME A-C. COMMUTATOR MOTORS WITH SERIES CHARACTERISTICS: I. THE REPULSION MOTOR

1942 ◽  
Vol 20a (5) ◽  
pp. 49-70
Author(s):  
E. G. Cullwick
Keyword(s):  
Power Factor ◽  
Maximum Power ◽  
Experimental Results ◽  
Finite Speed ◽  
Three Phase ◽  
Maximum Power Factor ◽  
Starting Torque ◽  
General Method

A general method, using "full reactances", is applied for developing the theory of the simple repulsion motor, the compensated repulsion motor, and the three-phase series motor. The effect of the currents induced in the armature turns short-circuited by the brushes is included, and is shown to affect profoundly the operation of the motors. Graphical constructions for the current loci are given, together with methods of measuring the various reactances, and of accounting for the effect of saturation. Experimental results for a three-phase series motor are included and compared with calculated values.Part I, published below, deals with the simple repulsion motor. Neglecting the effects of the coils short-circuited by the brushes, the usual well known results are obtained, and the position of the brushes for maximum starting torque is studied. The currents circulating in the coils short-circuited by the brushes are then found to have the following effects:(a) The performance of the motor, for a given current, is improved at speeds below synchronism, and is impaired at speeds above synchronism.(b) The maximum power factor is found to occur at some finite speed, whereas, if the effect of the short-circuited coils is neglected the power factor is a maximum at infinite speed.(c) The no-load speed is considerably lower than that usually associated with series motors.The rise and fall of the currents in the coils short-circuited by the brushes is studied in the Appendix.

scholarly journals A study on the behavior of beam-column connections in precast concrete structures: experimental analysis

2012 ◽  
Vol 5 (6) ◽  
pp. 848-873 ◽  
Author(s):  
M. N. Kataoka ◽  
M. A. Ferreira ◽  
A. L. H. C. El Debs
Keyword(s):  
Experimental Analysis ◽  
Precast Concrete ◽  
Concrete Structures ◽  
Concrete Cover ◽  
Experimental Results ◽  
Hollow Core ◽  
Multistory Buildings ◽  
Cracking Control ◽  
Hollow Core Slab ◽  
Reinforcement Distribution

Due to the large increase in the use of precast concrete structures in multistory buildings, this work covers a study on the behavior of beam-column connection with emphasis on the continuity provided by the slab reinforcement. Two prototypes were tested, each one with a different detail of the continuity reinforcement distribution. In both connections, the steel area used on the concrete cover of the hollow core slab was the same, varying the amount of bars that passed through the column and the ones that were placed adjacent to the column. The experimental results showed that the connection with bars adjacent to the column presented stiffness increase and a better cracking control. According to the classification the two tested connections can be considered semi-rigid.

Design and Experimental Analysis of Novel Refractometer Based on Photoelectric Sensor Technology

2011 ◽  
Vol 383-390 ◽  
pp. 5211-5215
Author(s):  
Yin Lin Li ◽  
Zhong Hua Huang ◽  
Kai Bo Hu
Keyword(s):  
Mathematical Model ◽  
Experimental Analysis ◽  
Differential Method ◽  
Theoretical Solution ◽  
Experimental Results ◽  
Sensor Technology ◽  
Photoelectric Sensor ◽  
Better Than

A novel refractometer based on photoelectric sensor technology and differential method is proposed. Sensing principle and mathematical model are introduced; structure and key parameters of sensing probe are designed through detail calculation. Theoretical solution shows resolution reaches order of 10-5. Preliminary experiments verify the feasibility of the design, experimental results show stability error better than ±1.02×10-4, error caused by temperature is 6.65×10-6/°C.

scholarly journals The Thermoelectric Solar Panels

2016 ◽  
Vol 3 (1) ◽  
pp. 9-14 ◽  
Author(s):  
R. Ahiska ◽  
L. Nykyruy ◽  
G. Omer ◽  
G. Mateik
Keyword(s):  
Electric Power ◽  
Internal Resistance ◽  
Solar Panel ◽  
Maximum Power ◽  
Experimental Results ◽  
Solar Panels ◽  
Photovoltaic Panel ◽  
Load Characteristics ◽  
Panel Surface

In this study, load characteristics of thermoelectric and photovoltaic solar panels areinvestigated and compared with each other with experiments. Thermoelectric solar panels convertsthe heat generated by sun directly to electricity; while, photovoltaic solar pales converts photonicenergy from sun to electricity. In both types, maximum power can be obtained when the loadresistance is equal to internal resistance. According to experimental results, power generated fromunit surface with thermoelectric panel is 30 times greater than the power generated by photovoltaicpanel. From a panel surface of 1 m2, thermoelectric solar panel has generated 4 kW electric power,while from the same surface, photovoltaic panel has generated 132 W only.

Failure of Polyurethane Foams under Different Loading Conditions

2008 ◽  
Vol 385-387 ◽  
pp. 205-208 ◽  
Author(s):  
Liviu Marsavina ◽  
Tomasz Sadowski ◽  
Dan Mihai Constantinescu ◽  
Radu Negru
Keyword(s):  
Mechanical Properties ◽  
Polyurethane Foam ◽  
Polyurethane Foams ◽  
Experimental Results ◽  
Loading Conditions ◽  
Sandwich Composites ◽  
Considerable Influence ◽  
Three Point Bending

Polyurethane foam materials are widely used as cores in sandwich composites, for packing and cushioning. This paper presents the experimental results obtained for the mechanical properties of polyurethane foams in different loading conditions and the influence of impregnation on the mechanical properties. A 200 kg/m3 density polyurethane foam was tested in tension, compression and three point bending. The experimental results show that the impregnation layer has no effect on the strength of the foam, but has considerable influence on the tensile and flexure modulus.

Experimental Analysis of Five Keel-Hull Combinations

1985 ◽  
Author(s):  
J. Gerritsma ◽  
J. A. Keuning
Keyword(s):  
Experimental Analysis ◽  
Model Tests ◽  
Experimental Results ◽  
Forward Speed ◽  
Hull Form ◽  
Towing Tank ◽  
Side Force ◽  
Performance Predictions

Model tests with five different keels in combination with one particular hull form have been carried out in the Delft Towing Tank. The variations include a plain deep keel, a keel-centre board, a plain restricted draft keel,a "Scheel" keel and a "winglet" keel. Based on the experimental results performance predictions are given for a 63 ft yacht for windspeeds up to 25 knots. The measured side force and resistance as a function of heeling angle, leeway angle and forward speed are used to analyse the relative merits of the considered keel-hull combinations.

Design and Implementation of Neuro-Fuzzy Controller Using FPGA for Sun Tracking System

2016 ◽  
Vol 12 (2) ◽  
pp. 123-136 ◽  
Author(s):  
Ammar Aldair ◽  
Adel Obed ◽  
Ali Halihal
Keyword(s):  
Optical Sensors ◽  
Fuzzy Logic Controller ◽  
Fuzzy Controller ◽  
Tracking System ◽  
Maximum Power ◽  
Experimental Results ◽  
The Sun ◽  
Fixed Angle ◽  
Pv Panel ◽  
Neuro Fuzzy

Nowadays, renewable energy is being used increasingly because of the global warming and destruction of the environment. Therefore, the studies are concentrating on gain of maximum power from this energy such as the solar energy. A sun tracker is device which rotates a photovoltaic (PV) panel to the sun to get the maximum power. Disturbances which are originated by passing the clouds are one of great challenges in design of the controller in addition to the losses power due to energy consumption in the motors and lifetime limitation of the sun tracker. In this paper, the neuro-fuzzy controller has been designed and implemented using Field Programmable Gate Array (FPGA) board for dual axis sun tracker based on optical sensors to orient the PV panel by two linear actuators. The experimental results reveal that proposed controller is more robust than fuzzy logic controller and proportional-integral (PI) controller since it has been trained offline using Matlab tool box to overcome those disturbances. The proposed controller can track the sun trajectory effectively, where the experimental results reveal that dual axis sun tracker power can collect 50.6% more daily power than fixed angle panel. Whilst one axis sun tracker power can collect 39.4 % more daily power than fixed angle panel. Hence, dual axis sun tracker can collect 8 % more daily power than one axis sun tracker.

scholarly journals Efficiency Analysis of Official Development Assistance Provided by Korea

2018 ◽  
Vol 10 (8) ◽  
pp. 2697 ◽  
Author(s):  
Yun-Gi Hwang ◽  
Soohyun Park ◽  
Daecheol Kim
Keyword(s):  
Development Assistance ◽  
Efficiency Analysis ◽  
Official Development Assistance ◽  
Qualitative Assessment ◽  
Tobit Regression ◽  
Average Efficiency ◽  
Positive Effects ◽  
Dea Efficiency ◽  
Low Efficiency ◽  
Tobit Regression Analysis

Results of the CDI and QODA evaluation developed by OECD showed that Korea’s aid presented low efficiency compared to other aid countries. However, these methods represent a qualitative assessment of the effectiveness of each country’s aid and are not applicable to the evaluation of actual aid projects and the identification of causes of the inefficiency. Therefore, it is needed to grasp the reality of Korea’s aid and to identify the cause of aid inefficiency to set up a better ODA policy. The purpose of this study is to improve the effectiveness of Korea’s Official Development Assistance (ODA) provided to developing countries. To do this, we analyzed the efficiency of ODA provided to 33 recipient countries by Korea through data envelopment analysis method. The effects of three factors, illiteracy, integrity, and GDP, on efficiency were also investigated by utilizing a Tobit regression analysis. As a result of the DEA efficiency analysis, it was found that the average efficiency was about 65.74%. By region, the average efficiency scores of Asia, Africa, Central and South America, and Middle East and Eastern Europe were about 47.8%, 78.9%, 70.4%, and 62.7%, respectively. This indicates that Asian countries are inefficient compared to countries from other regions. It was also found that GDP, integrity, and illiteracy have positive effects on efficiency. The methodology proposed in this study can be used for other studies to create an aid policy that produces efficient results.

Tuning the Thermoelectric Material’s Parameter: A Comprehensive Review

2020 ◽  
Vol 20 (6) ◽  
pp. 3636-3646
Author(s):  
Manoj Kumar ◽  
Sanju Rani ◽  
Yogesh Singh ◽  
V. N. Singh
Keyword(s):  
Thermal Conductivity ◽  
Power Factor ◽  
Thermoelectric Materials ◽  
Experimental Results ◽  
Thermoelectric Device ◽  
Thermoelectric Efficiency ◽  
Comprehensive Review ◽  
Waste Energy ◽  
Device Geometry

Thermoelectric is a device that converts heat into electricity. As thermodynamically it is not possible to make device which is 100 percent efficient, some amount of energy is wasted in the form of heat. Thermoelectric materials can play a major role in harnessing such waste energy. Although thermoelectric is a useful device still its efficiency is not good enough for commercialization. Therefore, lots of research have been carried out in finding out the best possible material, device geometry etc. There are thousands of papers describing various optimization processes. The present work reviews the basics of thermoelectric device parameters which determine the performance of the device and how to control these parameters for better thermoelectric efficiency. The efforts made to optimize parameters like power factor, thermal conductivity etc. have been summarized. Experimental results have been described with examples. Highest reported ZT values of various materials have been presented in this review.

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