Comparison of outflow boundary conditions for subsonic aeroacoustic simulations

Aeroacoustics simulations require much more precise boundary conditions than classical aerodynamics. Two classes of non-reflecting boundary conditions for aeroacoustics are compared in the present work: characteristic analysis based methods and Tam and Dong approach. In characteristic methods, waves are identified and manipulated at the boundaries while Tam and Dong use modified linearized Euler equations in a buffer zone near outlets to mimic a non-reflecting boundary. The principles of both approaches are recalled and recent characteristic methods incorporating the treatment of transverse terms are discussed. Three characteristic techniques (the original NSCBC formulation of Poinsot and Lele and two versions of the modified method of Yoo and Im) are compared to the Tam and Dong method for four typical aeroacoustics problems: vortex convection on a uniform flow, vortex convection on a shear flow, acoustic propagation from a monopole and from a dipole. Results demonstrate that the Tam and Dong method generally provides the best results and is a serious alternative solution to characteristic methods even though its implementation might require more care than usual NSCBC approaches

THE USE OF INFORMATION TECHNOLOGY TOWARD ONLINE TRANSACTION IN MICRO ENTERPRISE USING TECHNOLOGY ACCEPTANCE MODEL(TAM) FRAMEWORK

Technology Acceptance Model (TAM) is an adaptation of TRA introduced by Davis. The purpose of TAM is devoted to explaining the behavior of the users computer (computer usage behavior). The importance of internet and of the TAM antecedents of its website, however, change with experience. Aim of this study was to design and analysis the use of technology toward online transaction using TAM framework.In this research, the design of website of micro enterprises using TAM Framework. The sample is 15 respondents who make transaction online in Semarang.The method analysis use in this research is descriptive analysis. In this research used some technologies like: HTML, this is the basis of website. The result of this study HTML and CSS are used for the rapidly responsive website design. The results of the analysis is known that most of the respondents agreed on the use of online transaction technology using TAM framework. New findings/significance of contributionalmost all respondents agreed to answer the TAM framework applied in website design to facilitate online transactions. Keywords: information, technology, online transaction, TAM framework Technology Acceptance Model (TAM) adalah adaptasi TRA yang diperkenalkan oleh Davis. Tujuan TAM dikhususkan untuk menjelaskan perilaku pengguna komputer. Pentingnya internet dan pendahulunya TAM dari situs webnya, bagaimanapun berubah dengan pengalaman. Tujuan dari penelitian ini adalah untuk merancang dan menganalisa penggunaan teknologi terhadap transaksi online dengan menggunakan kerangka TAM.Dalam penelitian ini, perancangan situs web usaha mikro dibuat dengan menggunakan Kerangka TAM. Sampel yang digunakan adalah 15 responden yang melakukan transaksi online di Semarang. Metode analisis yang digunakan dalam penelitian ini adalah analisis deskriptif. Dalam penelitian ini digunakan beberapa teknologi seperti: HTML sebagai dasar website.Hasil penelitian ini HTML dan CSS digunakan untuk desain website yang cepat responsif. Hasil analisis diketahui bahwa sebagian besar responden sepakat mengenai penggunaan teknologi transaksi online dengan menggunakan kerangka TAM.Temuan baru / signifikansi kontribusi hampir semua responden menjawab setuju menggunakan kerangka TAM yang diterapkan dalam desain website untuk memudahkan transaksi online. Kata kunci: informasi, teknologi, transaksi online, kerangka TA

Understanding older consumers' usage of self-service technologies: test of two models

Self-service technologies play a major role in enabling consumers to perform service delivery themselves. This requires consumers adopting this service delivery process to modify their behaviour, however some consumers may resist change. Evidence of this is particularly strong in older consumers (plus 50 years of age) where their usage of self-service banking technologies (SSBT's) is considerably lower than for younger consumers. This paper specifically explores the beliefs, attitudes, intentions and usage behaviour of SSBT's by older consumers through the comparison of the suitability, fit and explanatory power of two existing models, namely the Theory of Planned Behaviour (TPB) (Ajzen 1991) and Technology Acceptance Model (TAM) (Davis, Bagozzi & Warshaw 1989). Survey methodology approach using a mailed questionnaire to 600 randomly selected respondents resulted in the return of 208 (35%) usable questionnaires. The use of SSBT's varied across the sample with 19% (40) non-users; 19% (40) low users (< 50% use); and 62% (128) moderate to high users (> 60%). The models were tested using AMOS 4.01 (Arbuckle & Wothke 1999), maximum likelihood estimation method. The TAM had a less than acceptable fit resulting in a modified TAM. The Modified TAM when compared with the TPB model had an overall better fit to the data in that all fit statistics were within acceptable limits and similar explanatory power. However, with the addition of two specific belief constructs in the modified TAM, perceived ease of use and perceived usefulness, these constructs provide a richer understanding of the factors that influence attitude (A), behaviour intention (BI) and behaviour (B) of older consumers' usage of SSBT's. Further, the failure of the perceived behavioural control pathway to contribute to the explanation of SSBT behaviour in the TPB model effectively gives the advantage to the Modified TAM. It is primarily for these reasons that the Modified TAM is favoured over the TPB model in this study

Dynamic test/analysis correlation using reduced analytical models

Test/analysis correlation is an important aspect of the verification of analysis models which are used to predict on-orbit response characteristics of large space structures. This paper presents results of a study using reduced analysis models for performing dynamic test/analysis correlation. The reduced test-analysis model (TAM) has the same number and orientation of DOF as the test measurements. Two reduction methods, static (Guyan) reduction and the Improved Reduced System (IRS) reduction, are applied to the test/analysis correlation of a laboratory truss structure. Simulated test results and modal test data are used to examine the performance of each method. It is shown that selection of DOF to be retained in the TAM is critical when large structural masses are involved. In addition, the use of modal test results may provide difficulties in TAM accuracy even if a large number of DOF are retained in the TAM

Faz hatalı SAR verileri için karesel olmayan düzenlileştirmeye dayalı bir görüntü oluşturma tekniği (A nonquadratic regularization based image reconstruction technique for SAR data with phase errors)

Sentetik Açıklıklı Radar (SAR) görüntülemesinde karşılaşılan önemli problemlerden biri faz hatalarıdır. Faz hataları, SAR’ın bulunduğu platformla hedef arasındaki uzaklığın tam olarak ölçülememesi ya da gönderilen işaretlerin atmosferdeki türbülansa bağlı olarak rasgele gecikmelere uğraması nedeniyle, SAR tarafından gönderilen sinyallerin hedefe gidip geri gelmesi için gereken zamanın tam olarak belirlenememesinden kaynaklanır ve oluşturulan SAR imgesinde çapraz menzil yönünde bulanıklaşmaya neden olurlar. Bu çalışmada, karesel olmayan düzenlileştirmeye dayalı bir çerçevede aynı anda hem görüntüleme hem de faz hatası kestirimi ile düzeltmesi yapan bir yöntem önerilmektedir. Yöntem, hem görüntüye hem de faz hatasına bağlı bir amaç fonksiyonunun eniyilenmesine dayanmaktadır. Deney sonuçları, önerilen yöntemin etkinliğini göstermektedir. --- One of the fundamental problems in Synthetic Aperture Radar (SAR) imaging is phase errors. Phase errors occur when the time required for the transmitted signal from SAR to the target and back cannot be obtained properly either because the distance between the SAR platform and the target cannot be measured exactly or in the case of random delays in the signal due to propagation in atmospheric turbulence. Phase errors cause blurring of the reconstructed image in the cross range direction. In this study, a nonquadratic regularization-based framework is proposed for joint image formation and phase error removal. The method involves the optimization of a cost function with respect to the image as well as the phase errors. Experimental results show the effectiveness of the proposed method

Ensuring cost-effective heat exchanger network design for non-continuous processes

The variation in stream conditions over time inevitably adds significant complexity to the task of integrating non-continuous processes. The Time Averaging Method (TAM), where stream conditions are simply averaged across the entire time cycle, leads to unrealistic energy targets for direct heat recovery and consequently to Heat Exchanger Network (HEN) designs that are in fact suboptimal. This realisation led to the development of the Time Slice Method (TSM) that instead considers each time interval separately, and can be used to reach accurate targets and to design the appropriate HEN to maximise heat recovery. However, in practise the HENs often require excessive exchanger surface area, which renders them unfeasible when capital costs are taken in to account. An extension of the TSM that reduces the required overall exchanger surface area and systematically distributes it across the stream matches is proposed. The methodology is summarised with the help of a simple case study and further improvement opportunities are discusse