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Energie aus Biomasse, meistens in Form von Holzkohle, wird im südlichen Afrika überwiegend von städtischen Haushalten mit niedrigem Einkommen verwendet. Durch steigendes Bevölkerungswachstum wächst der Druck auf den Wald. Anhand von Modellrechnungen wird analysiert, welche Einflüsse für die zunehmende Waldzerstörung verantwortlich sind und welche Strategien und Maßnahmen ergriffen werden können, um die Situation nachhaltig zu verbessern. Hierfür wurde die Modular Energy Systems Analysis and Planning Sofware (MESAP) verwendet. Das Wachstum der städtischen Bevölkerung ist als wesentliche Größe des zukünftigen Energiebedarfs anzusehen, da davon auszugehen ist, dass sich die Bevölkerung in Maputo, in Dar es Salaam und Lusaka in den nächsten 20 bis 30 Jahren verdoppeln wird. Der Haushaltsenergiebedarf in Maputo wurde 1980 bis 2000 zu 85-90% aus Holzprodukten gedeckt. In Dar es Salaam spielen Feuerholz, Elektrizität und Gas kaum eine Rolle. Der Holzkohleanteil ist hoch, jedoch zwischen 1980 und 2000 um 11% gesunken, der Paraffinanteil stieg um 12%. Die Haushaltsenergienachfrage von Lusaka erhöhte sich um 220% im gleichen Zeitraum und wurde zu 55% aus Holzkohle und 23% aus Feuerholz gedeckt. Unter der Annahme, dass die Tradition der Biomassenutzung weiter anhält, wird der Holzkohleverbrauch in Maputo im Jahr 2020 auf 240.000 t ansteigen und sich im Vergleich zum Jahr 2000 ebenso verdoppeln wie in Lusaka. In Dar es Salaam ist auf Grund des Bevölkerungsdrucks im gleichen Zeitraum mit einem Faktor von 2,3 auf 720.000 t zu rechnen. Durch die Einführung verbesserter Meilerbauweisen und Herde kann der Verbrauch erheblich reduziert werden. Damit könnte der Holzkohleverbrauch im Jahr 2020 in Maputo auf 180.000 t, in Dar auf 390.000 t und in Lusaka auf 260.000 t verringert werden. Im sambischen Untersuchungsgebiet lässt sich durch Verbreitung beider Strategien der Bedarf im Vergleich zum Referenzfall um bis zu 54% im Jahr 2020 reduzieren. Der Waldtyp im mosambikanischen Untersuchungsgebiet ist Savanne und unterscheidet sich deutlich von Tansania und Sambia, wo Miombo Wälder heimisch sind. Wachstumsraten von Savannenwäldern liegen mit maximal 57 t/km² a unter denen der Miombogebiete in Tansania und Sambia von 100 t/km² a. Da 90% des Holzkohlebedarfs aus dem mosambikanischen Untersuchungsgebiet bezogen werden, ergibt sich im Vergleich zu den anderen Ländern eine zusätzliche Brisanz. In Tansania kommen 80%, in Sambia lediglich 25% aus dem Untersuchungsgebiet. Ohne Maßnahmen und anhaltenden Druck auf die Untersuchungsflächen wird das Studiengebiet in Mosambik im Jahre 2018 vollständig entwaldet sein. Selbst eine Kombination der zuvor erläuterten Strategien mit allen forstwirtschaftlichen Maßnahmen kann eine fortschreitende Flächendegradation nicht aufhalten. Durch den Bevölkerungsdruck in Dar es Salaam wird der Entwaldungstrend im tansanischen Untersuchungsgebiet weiter anhalten. Aufgrund der Regenerationsfähigkeit der Miombo Bestände kann jedoch unter Einführung der beschriebenen Maßnahmen die weitere Degradation im Jahr 2015 aufgehalten werden. Im sambischen Untersuchungsgebiet ist der Einfluss durch das Köhlern am geringsten. Unter Durchführung eines Strategie Mix kann die ursprüngliche Dynamik in den Beständen im Jahr 2010 wieder erreicht werden. Diese Strategien sind nur durchsetzbar, wenn einerseits verbesserte Technologien in den Städten verfügbar sind und vertrieben werden. Andererseits muss die angrenzende Dorfbevölkerung die Umsetzung der forstwirtschaftlichen Pläne mittragen. Biomass energy, mostly in the form of charcoal, is used predominantly by low-income urban households in Southern Africa. Through its use, it places severe pressure on the natural woodlands from which it is obtained. This report analyses the development of the household energy sector under an ongoing use of charcoal and its influence on potential charcoal areas. The models for the cities of Dar es Salaam, Maputo and Lusaka were built with the help of the Modular Energy Systems Analysis and Planning software MESAP, which was developed at the Institute of Energy Economics and the Rational Use of Energy (IER). For each city, different options were simulated. The present research report contains the model part of the EU-project CHAPOSA (Charcoal Potential in Southern Africa) on basis of the data of the other partners and other references.

Prediction of daily global solar radiation with simple and highly accurate models would be beneficial for solar energy conversion systems. In this paper, we proposed a hybrid machine learning methodology integrating two feature selection methods and a Bayesian optimization algorithm to predict H in the city of Fez, Morocco. First, we identified the most significant predictors using two Random Forest methods of feature importance: Mean Decrease in Impurity (MDI) and Mean Decrease in Accuracy (MDA). Then, based on the feature selection results, ten models were developed and compared: (1) five standalone machine learning (ML) models including Classification and Regression Trees (CART), Random Forests (RF), Bagged Trees Regression (BTR), Support Vector Regression (SVR), and Multi-Layer Perceptron (MLP); and (2) the same models tuned by the Bayesian optimization (BO) algorithm: CART-BO, RF-BO, BTR-BO, SVR-BO, and MLP-BO. Both MDI and MDA techniques revealed that extraterrestrial solar radiation and sunshine duration fraction were the most influential features. The BO approach improved the predictive accuracy of MLP, CART, SVR, and BTR models and prevented the CART model from overfitting. The best improvements were obtained using the MLP model, where RMSE and MAE were reduced by 17.6% and 17.2%, respectively. Among the studied models, the SVR-BO algorithm provided the best trade-off between prediction accuracy (RMSE=0.4473kWh/m²/day, MAE=0.3381kWh/m²/day, and R²=0.9465), stability (with a 0.0033kWh/m²/day increase in RMSE), and computational cost.

In Bahasa Indonesia : Salah satu komponen pendukung dalam sistem pengapian pada motor bakar torak adalah busi. Pengapian dari busi terjadi karena adanya sumber energi listrik untuk menghasilkan energi aktivasi yang digunakan untuk membakar campuran udara dan bahan bakar sehingga menghasilkan tenaga. Busi sebagai suatu piranti untuk menghasilkan busur api listrik sangat berpengaruh terhadap kesempurnaan proses pembakaran yang terjadi didalam ruang bakar. Kesempurnaan proses pembakaran akan mempengaruhi unjuk kerja dari motor. Dengan menggunakan Busi Splitfire SF392D dan Kabel Busi Hurricane, maka waktu pengapian harus disesuiakan untuk mendapatkan daya yang optimal. Peningkatan daya rata-rata yang dihasilkan dari pengujian adalah 3,8%. Kata kunci: Busi, Kabel busi, energi aktivasi, peningkatan daya, penurunan konsumsi bahan bakar, proses pembakaran. One of supporting components in the ignition system of Spark Ignition Engine is spark plug. Ignition occurs caused by the existence of electric source energy which generates activation energy to ignite the air fuel mixture until produces power. Spark plug is a component generating the spark highly effected the completeness process in combustion chamber. The completeness of combustion process shall affects the performance of the engine. By using Splitfire SF392D Spark plug and Hurricane plug wire, the ignition timing must be resetting for optimum power result. From result of the test, everage power increased is 3.8%.

In Bahasa Indonesia : Salah satu komponen pendukung dalam sistem pengapian pada motor bakar torak adalah busi. Pengapian dari busi terjadi karena adanya sumber energi listrik untuk menghasilkan energi aktivasi yang digunakan untuk membakar campuran udara dan bahan bakar sehingga menghasilkan tenaga. Busi sebagai suatu piranti untuk menghasilkan busur api listrik sangat berpengaruh terhadap kesempurnaan proses pembakaran yang terjadi didalam ruang bakar. Kesempurnaan proses pembakaran akan mempengaruhi unjuk kerja dari motor. Dengan menggunakan busi dua elektrode dan busi tiga elektrode dapat meningkatkan unjuk kerja dari motor pada kondisi optimal khususnya peningkatan Efisiensi Thermis yaitu masing-masing 2,9% dan 3,7%. Kata kunci: Busi dua elektrode, busi tiga elektrode, energi aktivasi, peningkatan daya, penurunan konsumsi bahan bakar, proses pembakaran. One of supporting components in the ignition system of Spark Ignition Engine is spark plug. Ignition occurs caused by the existence of electric source energy which generates activation energy to ignite the air fuel mixture until produces power. Spark plug is a component generating the spark highly effected the completeness process in combustion chamber. The completeness of combustion process shall affects the performance of the engine. By using double electrode spark plug and multi electrode spark plug can increase the performance on optimal condition, particularly increasing of the thermal efficiency each is 2.9% and 3.7%.

Improving effectiveness turbine was and remains a key issue for today. In order to improve the efficiency of the turbine is necessary to reduce losses in the steam turbine exhaust conduit.This paper presents the design optimization exhaust conduit steam turbine K-27-2.9 produced by JSC «KTW» at the design stage. The aims of optimizing the design were: decreasing hydraulic resistance of the conduit, reduction of non-uniformity of the flow at the outlet of the conduit, equalizing steam flow ahead of the condenser tube bundle.The conduit models were made and flows in it were simulated in environment of the Solid Works and its application COSMOS Flo Works.As the initial conduit model was selected exhaust conduit of turbine PT-25/34-3.4 produced by JSC «KTW». Was obtained by the calculated velocity field at the outlet of the conduit. The analysis of the calculation results revealed the necessity of changes to the initial design of the conduit. The changes were accompanied by calculating currents flow in the conduit, and assessed the impact of design changes on the nature of the course. Further transformation of the construction of the conduit was held on the results of these calculations. Construction changes are not touched by the outer geometry of the conduit, and were introduced to meet technological.According to calculation results, conclusions were drawn and selected three versions of the conduit.Given are the research results for the initial conduit model and modified design versions. In order to evaluate the flow degree of irregularity the momentum factor (Bussinesku factor) for outlet crosssection of the selected conduit design version. Analysis of the research results made it possible to determine optimum design of the exhaust conduit.Introducing the suggested alterations in the conduit design will result in improvement of heat exchange in the condenser, an increase in reliability of the tube bundle operation, a decrease in noise and power losses, as well as a rise of the turbine plant efficiency in general.

The combination of the turning and burnishing process is an efficient approach to improve machined quality and productivity. This paper aims to optimize energy efficiency (EF), improved hardness ratio (IHR), and decreased roughness ratio (DRR) of a new hybrid turning-burnishing process. The machining parameters are the feed rate (f), turning speed (v), depth of cut (a), burnishing pressure (p), and the diameter of the compressing ball (d). A new turning-burnishing tool using compressed air has been designed and fabricated. A set of experiments for Aluminum Alloy 5083 were performed using the Taguchi method. The weightage principal component analysis (WPCA) and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) were applied to obtain the weight values and optimal outcomes. The results indicated that optimum values of the depth of cut, pressure, diameter, feed rate, and speed are 1.00 mm, 0.4 MPa, 16.00 mm, 0.084 mm/rev, and 120 m/min, respectively. The improvements in the EF and IHR are by 20.75% and 8.23% respectively, while the DDR is decreased by 19.05%, as compared to common values.

The aspect of dust accumulation on the surface of photovoltaic (PV) modules should be thoroughly understood in order to minimize possible obstacles affecting energy generation. Several elements affect the amount of pollutant gathered on the surface of a solar device, mainly its localization, which is irreversibly linked to factors such as annual rainfall, occasional snow coverage, or, in a dry climate, increased blow of dust during sandstorms and higher concentration of soil particles in desert areas. Other than weather conditions in the region, PV installation type also plays an important role as a more horizontal position is favorable for the accumulation of soil. The research carried out and presented in this paper was done for dust accumulated naturally on PV modules kept in outdoor conditions and dust artificially sieved onto the front glass cover of modules. The experiment performed by the authors, including artificially deposited dust, defined the linear relationship between surface dust density of different types of contaminants and efficiency decline up to 10% for two different PV modules. The additional field study carried out in external conditions for a coastal region in Northern Poland concluded that, after one year, exposition photovoltaic conversion efficiency can be over 10% lower, with a slight performance improvement for the autumn season characterized by heavy rainfall.

To reduce the condensation pressure of the refrigerant in the summer, refrigeration system has been developed, in which, during periods of high air temperature, the heat of condensation is removed to the coolant, which was pre-cooled at night due to radiative cooling. A methodology has been developed for determining the main characteristics of the elements of the proposed system and calculating its daily energy consumption. The calculation shows that the proposed system with a nominal refrigerating capacity of 10 kW, using the R404a refrigerant, allows in the climate of the city of Shymkent to reduce the condensation temperature to +32.9°C, and daily energy consumption by 6.5% compared to an ordinary vapor compression refrigeration machine.