Brushless electric motors are used intensively in the industrial automation sector due to the motors low inertia and fast response. According to the International Electrotechnical Commission, IEC ...60034-2-1, the efficiency of a three-phase electric machine (excluding machines for traction vehicles) can be determined by direct or indirect techniques. In the case of small traction motors (<10 kW), direct methods are used extensively by manufacturers, even if no standard has been published or scheduled by the IEC. In this paper, we evaluated the accuracy of the (direct) back-to-back method for the estimation of the energy performance of a 3 kW brushless AC electric motor used in a light electric vehicle. We measured the efficiencies of a pair of motors and inverters, as well as the overall efficiency of the entire power train. The results showed that the methodology was sufficiently accurate and comparable with other indirect methods available in existing literature. Moreover, we developed a Simulink model that used the powertrain efficiency map as the input to perform the simulation of a standard urban driving cycle. The simulation was run 500 times to calculate the probability density function associated with the total range of the vehicle, considering the uncertainty of the efficiency that was determined experimentally. The simulation results confirmed the low deviation of the distribution standard compared to the average value of the range of the vehicle.
Financial statements (balance sheet, profit and loss statement) intended for profit and non-profit organizations have large number of differences in terms of content of individual items and also with ...regard to their formal structure. This is due to the existence of different types of accounting entities for which there are created sets of accounting rules. Need for separate set of accounting rules results from their objectives, management rules, performed activities and certain specific of costs, revenues, assets and liabilities. The differences found on the basis of comparative analysis in this paper are evaluated and subsequently there are recommended changes of the statements so that they would be more useful for the purposes of economic analysis. The paper also identified problems that arise in connection with the evaluation of the efficiency of this type of organizations and subsequently there are recommended tools of financial analysis suitable for evaluation of non-profit organizations and the specifics of non-profit sector are pointed out. The paper presents also the proposal to change the Decree 504/2002 Coll. so as to avoid distortion of financial statement closing of non-profit organizations, and also with regard to their higher explanatory power.
This paper first deals with the measurement of technological innovation output and a detailed description of two-stage approach, the least squares method adopted in the first stage can estimate Cobb ...- Douglas production function of the industry and the resulting residuals are considered as the output indicators of the industries' technological innovation. In the second stage, the stochastic frontier model and the corresponding results drawn from the previous stage are used to estimate new technological innovation function of the entire industry, and the indexes of technological innovation efficiency in different industries are obtained accordingly. Subsequently, the technological innovation efficiency of the key industries in Hebei Province, including iron and steel, food, pharmaceutical, architecture and construction material, textile and garment, equipment manufacturing and petrochemical, is measured by means of this method. Lastly, the related proposals, according to the difference and developing trend of technological innovation efficiency index in different industries, on increasing technological innovation input and reasonable resources allocation are respectively put forward so as to improve the technological innovation efficiency and promote the development of key industries.
Proposes a model for partial report in which performance reflects the number of targets in a short-term memory buffer. The total number of items (targets, distractors, or extraneous noise) entering ...the buffer is independent of the number of targets and distractors in the stimulus. Entrance is determined by selective sampling according to a ratio rule developed by R. D. Luce (1959). The model was tested in a variety of conditions with partial reports based on brightness, color, shape, or alphanumeric class. Ss were 5 university students and staff. With 3 parameters, the model accounted for 99% of the variance with number of targets and number of distractors in data obtained by averaging across conditions. Parameter
K
(number of items entering the buffer) showed little variation with the selection criterion, and estimates for parameter |e (total impact of extraneous noise with impact per target as the unit) were rather small. Estimates for parameter |a (impact per distractor with impact per target as the unit) varied widely across conditions. Parameter |a is a measure for the efficiency of selecting targets rather than distractors. (30 ref)
A prototype of glazed flat plate solar collector with roll-bond absorber is presented and its performance is experimentally characterized. Differently from common sheet-and-tube collectors, in the ...present prototype the channels for the liquid are integrated in the roll-bond absorber plate. Measurements of thermal efficiency are reported for two samples of the prototype, one with a black coating on the absorber and the other with a semi-selective coating. Efficiency test runs have been performed in both steady-state and quasi-dynamic conditions, according to the standard EN 12975-2 (EN 12975-2. Thermal solar systems and components – solar collectors – part 2: test methods. Brussels: CEN; 2006). The efficiency measurements are compared with those taken for standard glazed flat plate collectors with sheet-and-tube absorber under the same test conditions. The experimental results show that the roll-bond absorber can provide higher performance. Besides, the thermal efficiency can be further increased and this is shown by means of a numerical model. The model is experimentally validated for standard flat plate collectors with sheet-and-tube absorber and for roll-bond collectors.
•Roll-bond solar collectors use an aluminium absorber plate with integrated channels.•Efficiency measurements on glazed flat plate roll-bond solar collectors are reported.•A new numerical model of flat plate collectors is presented and validated.•The effects of absorber coating and channels number are discussed.•The effect of ambient temperature on thermal efficiency curve is discussed.
Agricultural sector is considered to be one of the most important sectors in the Egyptian economy that contributes greatly in the national income. Therefore, the state pays great intention to the ...agricultural sector concerning all developmental aspects either vertical or horizontal. That is achieved through developing used and already existing agricultural resources which is called vertical agricultural development, or through adding new agricultural materials which is called horizontal agricultural development. In all of the abovementioned fields, agricultural machines play an important and direct role in achieving both vertical and horizontal agricultural development, as it is well- known that vertical and horizontal agricultural expand depends totally on agricultural machines in general and the developed modern machines in particular. As for vertical agricultural expand, agricultural machines play vital and effective role in increasing production, lowering production costs and the possibility of making use of the advantages and jumps of expansion through expanding in use and application of modern technical methods in agriculture as laser leveling, planting by seed drill, automatic seedling and automatic harvest. In addition to the abovementioned, there is the gab in the cereals, decrease of the net profit of farmers as well as their use of farming traditional methods that do not coop the agricultural development. Considering the importance of the technical standard as an important factor of agricultural production, the use of modern technology comes among the most important methods that may increase the production of Feddans by the optimal economic use of limited resources. The thesis aimed to introduce the best technical standards in agricultural machines applied in the farming rice, wheat and maize in order to yield the highest production with lowest costs and to gain the highest amount of net profit of Feddan. Moreover, the thesis aimed to study the production and economic indicators of the crops studied by the thesis and their development nationwide as well as comparing the effect of the technical processes on the productivity of the Feddan of the crops studied by the thesis and their effect from the economic feasibility point of view. This part of the thesis deals with the economic evaluation of using agricultural machines in order to farm to wheat in Egypt., as it was shown that the average Feddan productivity of wheat was estimated of about 3.7 ton/ Feddan as a result of using technical methods, whereas productivity by using traditional systems was about 2.8 ton/Feddan. This shows that as a result of using technological systems, Feddan productivity overcomes using the traditional systems as that increase was estimated to be about 0.9 ton/ Feddan with a percentage of about 32% from traditional systems. This increase in the average Feddan productivity for land unit reflects to new items, laser leveling, deep ploughing and adding land plaster with the relatively stability of varied production costs and the extent of technical and economic efficiency on favor of using technological systems. The thesis showed that the total proceeds of wheat farmed by using technological systems reached in average about 12440 pound/ Feddan, against 9560 pound/ Feddan for wheat farmed by using traditional systems. It was shown that the total proceeds of wheat farmed by using technological systems increase with a percentage of 30% from the same crop farmed by traditional systems. The study shows that the total varied costs of wheat for technological systems distributed on the production elements is estimated in average of about 3915 pound/ Feddan against 6390 pound/ Feddan for transitional methods with an increase of 39% when using agricultural machines. Moreover, the study pointed out that the total costs were estimated in average of about 5915 pound/ Feddan of wheat farmed by using technological systems against 8390 pound/ Feddan for traditional systems with an increase of about 29%. This illustrates the efficiency of suing technological systems. The study considered the net Feddan proceeds of wheat farmed by technological systems. It was estimated of about 6525 pound/Feddan against 1170 pound/ Feddan for traditional systems. This means that technological systems' net profit exceeds the same profits of traditional systems with an increase of about 5355 pounds. The study showed that the proceeds above the varied costs of wheat farmed by technological systems are estimated with about 8525 pound/ Feddan in average against 3170 pound/ Feddan for traditional systems. This means that technological systems are superior with about 169%. This increase is attributed to the increase in the total proceeds of technological systems comparing to traditional systems. The study shows that the cost of ton of wheat farmed by technological systems is estimated of about 3362 pound/ Feddan in average against 3414 pound/ Feddan for traditional systems. This means that technological systems exceed traditional systems with about 2%. This decrease is attributed to the increase of the Feddan productivity using technological system comparing to traditional systems. Considering the profit on the invested pound, it reached about 1.10 pounds for the use of technological systems against 0.14 pounds for the use of traditional systems. This shows that the technological systems used in farming wheat is better from both technical and economic point of view which means that the new technological systems used in production covers the total costs and realizing a surpass. This shows the efficiency of resource usage in producing wheat farmed by technological systems. Every pound being spent or invested in farming using technological systems achieves an income of about 10 pounds against one pound for traditional system.
In most developing countries like India, benchmarking of water supply utilities is rarely carried out as these services are not run on professional lines to ensure profitability, even as social goals ...of making provision for all, including the poor, take priority over profitability. When performances of these services are not measured, efforts to improve these services remain directionless and arbitrary. Urban water supplies in India, therefore, suffer a self‐inflicted fate, wherein city municipalities remain mired in mundane issues, leading to large dissatisfaction and inefficiencies. This paper attempts to evolve a framework for evaluating cost efficiencies of water supply services and applies stochastic frontier analysis to 18 urban centres in India through six models. The results indicate large relative inefficiencies and a scope of savings of 24.5% of average current operating and maintenance costs even with existing levels of resource inputs. The results are discussed from a regulatory and policy‐making perspective.
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