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Öğe 3-D Numerical Simulation of a Real Dam Reservoir: Thermal Stratified Flow(Springer-Verlag Singapore Pte Ltd, 2016) Unes, Fatih; Demirci, Mustafa; Varcin, Hakan[Abstract Not Available]Öğe Beton davranışında mikromekanik modelleme(2006) Örnek, Murat; Deliktaş, Babür; Caner, Ferhun Cem; Demirci, MustafaBetonun malzeme davranışı itibariyle son derece karmaşık bir yapıya sahip olduğu bilinmektedir. Betondan imal edilen yapıların başarılı bir şekilde tasarlanması beton davranışının daha'iyi modellenmesine doğrudan bağlıdır. Kullanılan malzeme modelinin gerçek davranışı temsil etmesi, özellikle yapı elemanlarının göçme yükleri hesaplanırken oldukça önemlidir. Bu amaçla geliştirilen birçok model malzeme mikromekaniğine dayanmaktadır. Bu çalışmada, betonun mekanik davranışı, mikromekanik yaklaşımla sayısal olarak modellenmiş ve sunulan modelin geçerliliği literatürde mevcut bir takım deneysel verilerle karşılaştırılarak araştırılmıştır.Öğe Experimental investigation of cross-shore sandbar volumes(Springer, 2014) Demirci, Mustafa; Akoz, M. Sami; Unes, FatihSandbars are critical to the cross-shore movement of sediment. Prediction of cross-shore sandbar volumes requires knowledge about the functional relationship of sediment transport rate conditions with waves, currents, base slope, sediment property and water depth. In this study, experiments on cross- shore sediment transport were carried out in a laboratory wave channel for initial base slopes of 1/8, 1/10 and 1/15. Using regular waves with different deep-water wave steepness generated by a pedal-type wave generator, bar volumes caused by cross-shore sediment transport are investigated for beach materials with the medium diameter of d(50) = 0.25, 0.32, 0.45, 0.62 and 0.80 mm. A non-dimensional equation for sandbar volume was obtained by using linear and non-linear regression methods through the experimental data and was compared with previously developed equations in the literature. The results have shown that the experimental data fitted well to the proposed equation with respect to the previously developed equations.Öğe Investigation of bar parameters occurred by cross-shore sediment transport(Soc Naval Architects Korea, 2013) Demirci, Mustafa; Akoz, M. SamiCross-shore sediment transport is very important factor in the design of coastal structures, and the beach profile is mainly affected by a number of parameters, such as wave height and period, beach slope, and the material properties of the bed. In this study cross-shore sediment movement was investigated using a physical model and various offshore bar geometric parameters were determined by the resultant erosion profile. The experiments on cross- shore sediment transport carried out in a laboratory wave channel for initial base slopes of 1/8, 1/10 and 1/15. Using the regular waves with different deep-water wave steepness generated by a pedal-type wave generator, the geometrical of sediment transport rate and considerable characteristics of beach profiles under storm conditions and bar parameters affecting on-offshore sediment transport are investigated for the beach materials with the medium diameter of d(50)=0.25, 0.32, 0.45, 0.62 and 0.80 mm. Non-dimensional equations were obtained by using linear and non-linear regression methods through the experimental data and were compared with previously developed equations in the literature. The results have shown that the experimental data fitted well to the proposed equations with respect to the previously developed equations.Öğe An investigation on the formation of submerged bar under surges in sandy coastal region(China Ocean Press, 2012) Demirci, Mustafa; Akoz, M. SamiCross-shore sediment transport rate exposed to waves is very important for coastal morphology, the design of marine structures such as seawalls, jetties, breakwaters etc, and the prevention of coastal erosion and accretion due to onoff shore sediment transportation. In the present study, the experiments on cross-shore sediment transport are carried out in a laboratory wave channel with initial beach slopes of 1/8, 1/10 and 1/15. By using the regular waves with different deep-water wave steepnesses generated by a pedal-type wave generator, the geometrical characteristics of beach profiles under storm conditions and the parameters affecting on-off shore sediment transport are investigated for the beach materials with medium diameters of d (50)=0.25, 0.32, 0.45, 0.62 and 0.80 mm. The offshore bar geometric characteristics are the horizontal distances from the shoreline to the bar beginning (X (b)), crest (X (t)), and ending (X (s)) points, the depth from the bar crest to the still water level (h (t)), and the bar volume (V (bar)). The experimental results have indicated that when the deep-water steepness (H (0)/L (0)) increased, the net movement to seaside increased. With the increasing wave steepness, the bars moved to widen herewith the vertical distances from still water level to the bar beginning (X (b)), crest (X (t)) and ending (X (s)) points and the horizontal distances from the coast line to the bar beginning, crest and ending points increased. It was also shown from experimental results that the horizontal distances from the bar beginning and ending points to the coast line increased with the decrease of the beach slope. The experimental results obtained from this study are compared with previous experimental work and found to be of the same magnitude as the experimental measurements and followed the expected basic trend.Öğe Perceptions of Turkish construction firms about the marketing concepts(Vilnius Gediminas Tech Univ, 2015) Erdis, Ercan; Coskun, Hilmi; Demirci, MustafaCompetitive marketing environment requires construction companies to come up with the right strategies to progress. This only becomes possible by preparing rigorous preconstruction feasibility studies. Additionally, the effectiveness of promotion activities of the company is important to acquire a market share which can be realized by having systematic marketing concept. In this study, the perception and application level of marketing concept of construction firms are investigated. The promotion strategies which enable the companies to have systematic applications of marketing concepts in order to compete with other companies in the sector are discussed. To evaluate the marketing attitudes as applied by the companies, a questionnaire was performed with forty nine Turkish construction firms. The perception and application of the marketing are discussed based on the organizational structure and key interest areas of construction companies. The overall result deduced is that the construction companies do not have a systematic approach to marketing. The companies have primarily adopted the approaches to keep their current places in the sector.Öğe Prediction of cross-shore sandbar volumes using neural network approach(Springer Japan Kk, 2015) Demirci, Mustafa; Unes, Fatih; Akoz, M. SamiCorrect estimation of bar volumes, wave height, wave period and median sediment diameter is crucial for the designing of coastal structures and water quality problem. In this study, bar volumes caused by cross-shore sediment transport were investigated using a physical model and obtained 64 experimental data considering the wave steepness (H (0)/L (0)) and period (T), the bed slope (m) and the sediment diameter (d (50)). Artificial neural network (ANN) and multi-linear regression (MLR) are used for predicting the bar volumes. A multi layer perceptron is used as the ANN structure. The results show that the ANN model estimates are much closer to the experimental data than the MLR model estimates.Öğe Prediction of Millers Ferry Dam Reservoir Level in USA Using Artificial Neural Network(Budapest Univ Technology Economics, 2015) Unes, Fatih; Demirci, Mustafa; Kisi, OzgurReservoir level modeling is important for the operation of dam reservoir, design of hydraulic structures, determining pollution in reservoir and the safety of dam. In this study, daily reservoir levels for Millers Ferry Dam on the Alabama River in USA were predicted using artificial neural networks (ANN). Bayesian regularization backpropagation training algorithm is employed for optimization of the network. The results of the optimal ANN models were compared with conventional auto-regressive models (AR), auto-regressive moving average (ARMA), multi-linear regression (MLR) models. The models are compared with each other according to the three criteria, namely, mean square errors, mean absolute relative error and correlation coefficient. The comparison results show that the ANN models perform better than the conventional models.Öğe Prediction of suspended sediment in river using fuzzy logic and multilinear regression approaches(Springer, 2013) Demirci, Mustafa; Baltaci, AhmetPrediction of sediment concentration in a river is very important for many water resource projects. Conventional sediment rating curves (SRC), however, are not able to provide sufficiently accurate results. In this paper, a fuzzy logic approach is proposed to estimate suspended sediment concentration from streamflow. A comparison was performed between fuzzy logic (FL), SRC and multilinear regression models. It was based on a 5-year period of continuous streamflow, suspended sediment concentration and mean water temperature data of Sacremento Freeport Station operated by the United States Geological Survey. Based on the comparison of the results, it is found that the FL model gives better estimates than the other techniques.Öğe PRICING POLICIES AS A MARKETING STRATEGY IN THE CONSTRUCTION INDUSTRY: CASE STUDY OF TURKISH COMPANIES(Vilnius Gediminas Tech Univ, 2013) Coskun, Hilmi; Erdis, Ercan; Demirci, MustafaThe firms in the construction industry have to determine pricing and promotion policies, then these policies must be carefully and systematically integrated with the marketing strategies. Not only the demand and cost are important in pricing decisions but competition is also a significant variable to be considered. To determine the difficulties and the affecting factors in applying pricing decisions within the marketing concepts in construction sector, a survey was carried out among the Turkish companies as a sample group. In total 49 companies, mostly medium-size firms have been surveyed. The responses of firms are considered based on their actively engaged subsectors, namely, residential, commercial/public buildings, and infrastructure construction. The answers of firms are also evaluated based on their stated organizational structure, namely, simple, hierarchical, project, and network. The views about the various aspects of pricing policy development in phases, for example before and during bid, differ in the construction companies depending on their actively involved fields and their organizational structures.Öğe Smart Grid on Energy Efficiency Application for Wastewater Treatment(Wiley-Blackwell, 2014) Kebir, Fatih Onur; Demirci, Mustafa; Karaaslan, Muharrem; Unal, Emin; Dincer, Furkan; Arat, H. TuranIn this study, first, designing and operating conditions of a wastewater treatment plant located in the south of Iskenderun of Hatay, Turkey, is examined and analyzed. It is shown that influent pumps have large part of energy consumption in plant. Second, some simulation and experimental studies were performed on plant. Energy efficiency and plant optimization have provided 40% of energy consumption. Also, experimental study is simulated by Matlab Fuzzy LogicController. The experimental results are in good agreement with the simulation results. (c) 2013 American Institute of Chemical Engineers Environ Prog, 33: 556-563, 2014Öğe Suspended sediment estimation using an artificial intelligence approach(Springer International Publishing, 2015) Demirci, Mustafa; Üneş, Fatih; Saydemir, SebahattinForecasting of sediment concentration in rivers is a very important process for water resources assignment development and management. In this paper, a neural network approach is proposed to predict suspended sediment concentration from streamflow. A comparison was performed between artificial neural network, sediment rating-curve and multilinear regression models. It was based on a 5 years period of continuous streamflow, suspended sediment concentration and mean water temperature data of West Virginia, Little Coal River, Danville station operated by the United States Geological Survey. Based on comparison of the results, it is found that the artificial neural network model gives better estimates than the sediment rating-curve and multilinear regression techniques. © Springer International Publishing Switzerland 2015.Öğe Türk inşaat firmalarının sistematik pazarlama anlayışını etkileyen faktörler(2008) Erdiş, Ercan; Demirci, Mustafa; Kılıç, Arzu; Örnek, MuratGünümüzde eğitim ve teknolojideki ilerlemeler, toplumun refah düzeyindeki artıs müsterilerin daha kaliteli binalar talep etmesine neden olmaktadır. Bu durum insaat sektörünün içinde bulunduğu rekabetçi pazar ortamında sirketlerin doğru projelerle ve doğru fiyatlandırma anlayısı ile müsterilerin karsısına çıkmasını gerektirmektedir. Bu da ancak sirketlerin insaat öncesi ön hazırlık çalısmalarının titizlikle yürütmesi ile mümkün olmaktadır. Bunun yanında sirketin kisisel satma ve tutundurma faaliyetlerinin (reklâm, firmanın tanıtımını yapacak aktiviteler vb.) etkinliği de olusan bu pazarı elde etmek için önem arz etmektedir. Sirketin sistematik bir pazarlama anlayısına sahip olması, diğer bir deyisle kendi bünyesinde kendisini diğer sirketlerden ayrılmasını sağlayacak değerler insa etmesi ile mümkün olacaktır. Bu arastırma kapsamında insaat sirketlerinin pazarlama kavramını algılama ve uygulama düzeyi incelenmistir. Sirketlerin pazar içinde ve rakip firmalarla etkili bir biçimde rekabet etmelerini, sistematik bir pazarlama anlayısına sahip olmasını sağlayacak doğru fiyatlandırma ve tutundurma stratejileri üzerinde durulmustur. Sirketlerin bu yönde bir yönetim tarzı sergileyip sergilemedikleri ile ilgili değerlendirmede bulunabilmek için insaat sektöründe yer alan orta ve büyük ölçekli 50 firma ile bir anket çalısması düzenlenmistir. Anketin amacı, öncelikle insaat firmalarının pazarlama sürecini etkileyen fiyatlandırma ve tutundurma stratejilerini belirlemektir. Anket çalısması sonucunda ayrıca, firmaların pazarlama sürecini algılama ve uygulama düzeyleri ve uygulamadaki eksiklikleri ortaya çıkarılmıstır. Sonuçlar, literatür bulguları ısığında değerlendirilmistir.Öğe Türk inşaat sektöründe pazarlamaya verilen önem ve ihale öncesi teklif hazırlama stratejileri(Hatay Mustafa Kemal Üniversitesi, 2001) Demirci, Mustafa; Oral, EmelBu çalışmanın amacı Türk inşaat sektöründe pazarlamaya verilen önemi saptamak ve inşaat şirketlerini başarıya götürecek pazarlama stratejilerini ortaya çıkarmak, özellikle teklif hazırlama stratejilerini belirlemektir. Bu çalışmada pazarlama, pazarlama stratejileri ve inşaat şirketlerinde ihale öncesi teklif hazırlama stratejilerinin tanımı için literatür çalışması yapılmıştır. Bu çalışmanın ilk kısmında pazarlamanın temel tanımı işlenmiş, diğer kısımlarında ise teklif hazırlama stratejileri irdelenmiştir. Türk inşaat sektöründe pazarlamaya verilen önemi saptamak amacıyla, küçük ölçekli inşaat şirketlerini içeren bir anket çalışması yapılmıştır. Anketten müteahhitlerin büyük çoğunluğunun pazarlamayı reklamcılık olarak algıladığı; teklif hazırlama aşamasında ise genelde şirketlerin belirli bir stratejiye sahip olmadıkları belirlenmiştir. Tezin sonuçları için ise literatür ve anket bulguları değerlendirilmiş ve şirketleri başarıya götürecek ekili pazarlama stratejileri belirtilmeye çalışılmıştır. Anahtar kelimeler : İnşaat sektörü, pazarlama, pazarlama stratejileri, teklif hazırlama stratejileri, istatistiksel analizler
