bluuebunny/crossref_metadata_2025_split huggingface dataset:
Boundary Layer Separation Control on an Inclined Plate Using Jet and Vortex Actuator
Authors: Cadirci Sertac , Gunes Hasan 
Published: April 2014

In this numerical study a Jet and Vortex Actuator (JaVA) system is implemented on an inclined plate (with an inclination angle 6°) to control the laminar boundary layer separation. JaVA is an active flow control device similar to the synthetic jets that transports momentum into the boundary layer and interacts with the boundary layer velocity profiles.
The JaVA used in this study is a two-dimensional rectangular cavity with an actuating plate mounted on the opening which is placed asymmetrically. The plate moves up and down in vertical direction with a specified frequency. As the actuating plate is mounted asymmetrically on the cavity-opening, there are one narrow (wn) and one wide gap (ww) between the plate and the cavity.
First JaVA in a cross-flow on an inclined plate (with inclination angle 6°) is modeled using a computational domain including a moving zone to mimic the vertical motion of the actuating plate. As plate moves up and down like a piston, JaVA-induced vortices emanate from the wide gap and are injected into the oncoming boundary layer.
The calculations are carried out by a commercial finite-volume-based unsteady, laminar, incompressible Navier-Stokes solver. Time-averaged flow fields are calculated to extract boundary layer profiles from various downstream stations. For different oscillation frequencies (f = 1, 2, 3 and 4 Hz) time averaged boundary layers are compared to the non-actuated case (f = 0). The variations of the important boundary layer characteristics (displacement thickness, momentum thickness, shape factor) as well as friction coefficient are also investigated. It is observed that with increasing plate frequency or jet-Reynolds number (ReJ = 4abf/ν), JaVA-induced vortices interact with the cross-flow and modify the boundary layer characteristics. This has been shown in the time-averaged velocity profiles with a fuller shape causing larger displacement thicknesses and in association with them the shape factors drop and the friction coefficients increase.
The proposed control method based on alternating suction and blowing with an oscillating plate is effective in delaying or preventing the flow separation downstream of an inclined plate.
Federative Data Management Based on Unified XML Data Scheme to Support Prosthetic Dentistry Workflows
Authors: Heister Reinhard , Anderl Reiner 
Published: April 2014

The laboratory side of a digital dental workflow consists of heterogeneous software tools including digitization (scanning), modeling (CAD), production planning (CAM) and production. The heterogeneity can be structured in two dimensions: ‘various partial systems’, composing the dental product development system and ‘various vendors’, offering software solutions for these partial systems. As a result the value creation process lacks efficiency and different input/output data streams are still necessary. As a standard for the representation of geometric data the STL format has been established, whereas for additional information, such as organizational and administrative data, as well as requirements and design data, the XML (eXtensible Markup Language) format is considered appropriate. However, a variety of proprietary XML data formats have been developed by system vendors. Thus incompatibilities are a significant source for errors. Data flow structures as available today only allow unidirectional flow of information ‘downstream’.
A new approach is based on a federative workflow data management. The basic concept is a unified XML scheme that represents data about all activities and states of dental objects created throughout the whole cycle of dental process. The new unified XML scheme provides a data structure, which can be adapted for the respective input/output data streams of all partial systems. The XML scheme represents a unified data scheme which allows both vertical (within a certain partial system class) and horizontal (along the digital dental workflow and independent of system vendor) data usage. Each dental system supplier only needs to create one input and output filter for the neutral XML interface. The system architecture is based on a web server to which a XML database server is connected. The XML database server manages project specific XML databases. Data can be made available through REST-, as well as through WebDAV-interface on LAN or WAN. With the help of XPath and XQuery required data can be extracted from the database. Redundant data input as well as incompatibility errors can be avoided by this approach.
The innovative core is a unified workflow data format, in which a bidirectional data flow can be provided for both downstream and upstream, along the digital dental workflow.
A Moving Frame Method for Multi-Body Dynamics
Authors: Murakami H. 
Published: April 2014

Élie Cartan’s moving frame method, developed in differential geometry, has been applied to multi-body dynamics to derive equations of motion. The explicit representation of a body-attached orthonormal coordinate basis and its origin, referred to as a moving frame, enables the usage of the special orthogonal group, SO(3), and the special Euclidean group, SE(3), to describe kinematics and kinetics of interconnected bodies by joints and force elements. The moving frame representation using Theodore Frankel’s compact notation is adopted to alleviate theoretical complexities of the Lie group theory to which SO(3) and SE(3) belong. For the variational formulation, the restricted variation of angular velocity is derived for the moving frame method.
Starting from two connected rigid bodies, it will be demonstrated that the explicit representation of moving frames renders straight-forward symbolic computations of three-dimensional kinematics and kinetics. This simplicity eliminates errors in computing analytical expressions for kinematic and kinetic variables and streamlines the coding effort for numerical solution. For controller design, if the degrees-of-freedom is small, the moving frame method allows a straight-forward derivation of equations of motion in analytical form.
A Mathematical Model for a Gyroscopic Ocean-Wave Energy Converter
Authors: Murakami H. , Rios O. 
Published: April 2014

Global attempts to increase generation of clean and reproducible energy have contributed to considerable progress in ocean-wave power-generation technologies. The efficiency of ocean-wave energy converters has improved by almost an order of magnitude in the last decade. In this report, we consider a floating-type gyroscopic ocean-wave power-generator that has proven to generate 50 kW in a prototype test conducted by a Japanese company in 2012.
A gyroscopic power generator consists of a buoy, a gimbal, and spinning rotors mounted on a gimbal. The gimbal is installed on the deck of the buoy and rotates when the buoy oscillates or rocks by ocean waves. The gimbal axis is connected to an electric generator.
The objectives of our research are to understand quantitatively the mechanisms of gyroscopic ocean-wave power-generators and to improve the component design of the generator to maximize power output. To this end, we develop a mathematical model and a scale model of a gyroscopic ocean-wave power-generator. This integrated approach is to numerically simulate power generation and to clarify the effect of relevant design parameters.
An International Outlook of Innovative Energy Efficient Designs of Low Carbon Buildings
Authors: Khalil Essam E. 
Published: April 2014

The Developing communities in their path for rapid development is endeavoring to make all necessary and appropriate measures to enhance the efficiency of energy utilization and increase the beneficiation of the energy resources. The energy production, transmission, distribution and utilization efficiency becomes a vital factor and measure of national development. Governmental organizations were established earlier to be responsible for energy planning and efficient utilization, information dissemination and capacity building as well as devising the necessary codes and standards. Throughout the Nation Energy resources are widely used and consumption rates are in general exceeding the International accepted values. Energy rationalization and audit exercises were developed and monitored by Governmental authorities, Universities and Research centers through the past two decades with a definitive positive energy reduction and beneficiation. The development of the relevant codes for Residential and Commercial Energy Efficiency in Building is underway through the governmental bodies responsible for the research and development in the building Technology sector and is the umbrella under which the National and Unified Arab Codes are developed and issued. A proposed new Energy Performance in Buildings Directive based on relevant ISO, ASHRAE and LEED would be beneficial to practitioners to meet the following targets of Energy Performance Directive:
1. “Legestilative authorities shall ensure that, when buildings are constructed, sold or rented out, an energy performance certificate should be made available to the owner.
2. The energy performance certificate for buildings shall include reference values such as currant legal standards and benchmarks in order to make it possible for consumers to compare and assess the energy performance of the building. The certificate shall be accompanied by recommendations for cost-effective improvement of the energy performance…”.Ultimately a unique energy standard is sought for Middle East region to harness the energy consumption. This can be achieved by developing methodologies for energy declaration of the buildings and to provide a labeling system and energy signature for selected buildings.
Vibration Effects on Surface Coke Deposition of Hydrocarbon Fuel at Supercritical Pressure Condition in Micro-Tubes
Authors: Fu Yanchen , Tao Zhi , Xu Guoqiang , Deng Hongwu 
Published: April 2014

Experiments are performed to study vibration effects on surface coke deposition of aviation hydrocarbon RP-3 under supercritical pressure. The flowing RP-3 kerosene is stressed to 5MPa, and heated up from 127°C to 450°C in a stainless tube (1.8mm I.D., 2.2mm O.D., 1Cr18Ni9Ti) with a constant heat flux, and the mass flow rate is 3g/s. The working fluids flow downward through an 1800mm long tube. The vibration frequency is set from 100Hz to 600Hz, covering the main frequencies of the combustion chamber vibration when it works. Compared with stable condition, vibration effects have a distinct impact on the flow resistance and heat transfer.
The amount of coke deposition reduced under all different frequencies with the maximize decline of 40.46%. Moreover, restraining efficiency is proportional to the vibration energy. Besides, vibration enhanced the heat transfer, the coefficient of which comes to a wave crest at the zone of second-order modes of response to the peak area with the biggest vibration energy.
Dynamic Analysis of a Dual-Mode CO2 Heat Pump With Both Hot and Cold Thermal Storage
Authors: Houbak-Jensen Lars , Holten Anders , Blarke Morten Boje , Groll Eckhard A. , Shakouri Ali , Yazawa Kazuaki 
Published: April 2014

We investigated the dynamics of a transcritical CO2 heat pump system including hot and cold thermal storages, which makes up the concept “thermal battery”. The analytical model is used for the study of the dynamics of the system involving simultaneous supply of heating and cooling for buildings. The model includes the dynamics of the gas cooler, evaporator and the thermal storages, while the compressor and the expansion valve are considered quasi-static. The heat transfer in the dynamically modeled components is described by partial differential equations (PDEs) consisting of heat conduction, convection, and source terms. Each component is divided into a number of volumes adjusted according to the required precision and reasonable computational time. We applied two discretization schemes in order to find a numerical solution to the PDEs. The spatial discretization for the heat exchangers is performed by using the upwind scheme, where the fluid properties are individually calculated within each volume. Due to the discrete events in form of tapping and loading (or charging and discharging) of the heat storages, the discretization approach takes into account the sharp spatial transitions within the thermal storages. Therefore, the method of lines in combination with the Superbee slope-limiter was applied for the spatial discretization for high resolution calculation. The modeling approach results in a set of algebraic and ordinary differential equations (ODEs), hence the model becomes an algebraic differential equation problem, which we solved by using MATLAB solver ODE15s.
This extended model was used to simulate a dynamic response of the case with varying heating and cooling consumption over a period of 24 hours in a building. The heating and cooling energy consumption follow a sinusoidal and continuous pattern. The results include the effect on both the outlet temperatures and the system coefficient-of-performance (COP). The outlet energy from the hot storage and the cold storage is used for heating tap water and a chilled water space cooling application subject to temperature requirements. Dimensioning of both storages is crucial for obtaining the required temperatures. The model identifies the critical storage levels required to satisfy the periodic but out-of-phase combination of heating and cooling demands. The volume of the cold storage will have to be considerably larger than the hot storage due to the lower temperature difference.
Production, Characterization and Application of Meso-, Micro- and Nano-Scaled Surface Structured Devices for Boilers and Heat Exchangers
Authors: Beyer M. , Kölling A. , Kohn S. , Nowitzki M. , Sagasser H. , Hellwig U. , Sachno N. 
Published: April 2014

In this paper we report on the investigations of 48 tubular and 3 planar meso-, micro- and nano-scaled surface structured devices for boilers and heat exchangers made of steel, copper and brass.
The tubular structured components are object of protective right in terms of industrial power tube (ip tube). Hexagonal types with sinusoidal structures and roughness values in the order of bts/dHyd = 0.3 used for heating of a fluid by a fluid proved to have a heat transmittance of k = 1737 W · m−2 · K−1 and to be increased by 47 % compared to the corresponding value of a smooth tube k = 1182 W · m−2 · K−1.
Dodecahedronal closed structured tubes with smaller roughness of bts/dHyd = 0.1 used for falling film evaporation showed a heat transmittance of k = 5130 W · m−2 · K−1 corresponding to an increase by 19 % depending on the Reynolds number Re between 7100 and 17600.
Types of micro-structured tubes with 1000000 straight pins per square centimeter investigated in boiling experiments with Solkatherm SDS 36 at 0.7 bar appeared to have a decreased temperature excursion by 21 %, while there is a 25 % greater boiling resistance at low heat fluxes of about 25 W.
Steam condensation experiments were performed using copper tubes fabricated both with meso-scaled structures and 1000 straight pins per square centimeter. At a subcooling temperature of ΔT = 60 K at 1.1 bar the heat flux density proved to be increased by 340 % to a value of k = 420 kW · m−2 · K−1 compared to the conventional component. In addition the formation of droplets with a diameter of 0.003 m was observed. The numerical calculation of the local heat transfer coefficient at the interior wall resulted in a value of αi = 11.4 kW · m−2 · K−1. Micro-scaled tubular devices with 3.3 million crossed pins per square centimeter made of copper were investigated with respect to heterogeneous catalysis of carbon monoxide under oxidizing conditions at 478 K and 1 bar. The achieved yield measured by CO conversion rate was equal to the unit value with a delay time of 17000 s due to an initial oxygen layer at the surface.
Prototypic air cooled hot gas coolers were developed, constructed and evaluated, configurated with steel tubes and a small number of conical structures with a roughness of bts/dHyd = 0.01–0.03. By experiments using a biomass gasification test facility the heat transmittance of one cooler model proved to be increased by 22 % to a value of k = 11 W · m−2 · K−1. The corresponding pressure loss was so small that the effectivity of the applied measures to enhance heat transfer had a value of about 10 %. Moreover the formation of deposits on the side of the raw gas was found to be suppressed by 40 % to a fouling rate of 1.1 Mas.-% of the initial freight.
Dynamic Analysis of a Jack-Up Rig, SDOF Approach: Design Consideration — I
Authors: Godoy Francisco J. , Lorenzo Fernando 
Published: April 2014

A jack up rig, such as those used for oil drilling in the Gulf of Mexico, is a dynamic sensitive system subjected to random and periodic environmental loads (wave, wind, current, etc.), in which the inertia forces cannot be ignored. However, a static load analysis approach can be justified only if an extra inertial load set, due to the dynamic effect response, is included in the analysis. The Society of Naval Architects and Marine Engineers, SNAME T&R 5-5A, “Guidelines for Site Specific Assessment of Mobile Jack-Up Units”[1], addresses the calculation of the inertial load set by using the classical Single Degree of Freedom (SDOF) analogy to calculate such dynamic effect.
This study evaluates how far apart crucial structural members’ stresses/loads obtained by using the SDOF analogy method are from those values obtained from a more realistic modal dynamic analysis. The analysis is performed for wave loads at different heights and frequencies such as those existing on extreme or severe design conditions as a storm. Although a jack up rig structure presents some non-linearities, especially in the legs-hull contact areas and the spud-cans interaction with the soil; a modal superposition analysis can be used if proper linearization is considered.
The results of this study for a jack show that the SDOF analogy method tends to underestimate the base shear loads for high wave periods and conversely overestimate some stresses on crucial members, such as the legs’ chords close to the hull for all the wave periods.
This study shows that the stresses on one of the legs’ chord of the most loaded leg, due to the dynamic effect produced by the harmonic loads calculated with the SDOF analogy developed in this study tend to be overestimated as the wave period decreases. Conversely, the calculation of the base shear of the structure employing a quasi-static analysis with inertial load set (ILS) as calculated in this study shows that the base shear forces difference between the modal dynamic analysis and the quasi static analysis tends to decrease as the periods of the wave decreases.
Virtual Tools for Safety and Ergonomic Evaluations of Electric Vehicle Architecture
Authors: Kulkarni Ambarish , Kapoor Ajay 
Published: April 2014

Electric vehicles (EV’s) are alternative fuel technology in auto industry with wide acceptance across globe. This paper elaborates virtual methods used to as tool for safety and ergonomic evaluations of in wheel design using Switch Reluctance Motor (SRM). In our recent research, a unique design of in wheel design using SRM has been developed. Special advantages of this design include modularity, scalability, cost effectiveness, and easy installation. Easy installation of in wheel design architecture is one of the prime criteria, since it relates to changing of tyres in long runs. In the proposed passenger car, if work is carried out for maintenance issues, generally single operator (mechanic) dose tyre changing or wheel/brake servicing. Two validations are important, mainly safety of the operator; secondly design for assembly of motor, and tyre rims. As a part of this research, Virtual Reality (VR) based safety and ergonomic evaluation studies have been conducted for the in wheel design adaptations. The computational models and virtual modelling simulations using motion capture, Arena and EON reality mimicked live system environments, so as to validate effectiveness motor assembly and disassembly functionality using human as an interface.
Initial phase consists of schematic representations of models to evaluate conceptualisation for different designs. Based on schematics, SR motor and rim tyre models were developed and interfaced in VR environment. In second phase, vehicle topology was reverse engineered using hand held 3D scanner and converted to metafile for full scale model development. In third phase, motion capture was used with 20 camera systems to video record the existing human movements and rigid body such as tyre to develop live environment. Finally all three phases were interfaced together in VR environment to evaluate assembly and disassembly functions. Based on the validation of these, designs were fine tuned for effective assembly functionality. The VR based safety and ergonomic evaluation procedures were used for demonstration of wheel assembly disassembly functions by single operator. Similar context can be extended to other automotive design evaluations, without substantial prototype costs for safety and ergonomic evaluations.
Damage and Failures of CGA/BGA Assemblies Under Thermal Cycling and Dynamic Loadings
Authors: Ghaffarian Reza 
Published: April 2014

Commercial-off-the-shelf column/ball grid array packaging (COTS CGA/BGA) technologies in high-reliability versions are now being considered for use in high-reliability electronic systems. For space applications, these packages are prone to early failure due to the severe thermal cycling in ground testing and during flight, mechanical shock and vibration of launch, as well as other less severe conditions, such as mechanical loading during descent, rough terrain mobility, handling, and ground tests. As the density of these packages increases and the size of solder interconnections decreases, susceptibility to thermal, mechanical loading and cycling fatigue grows even more.
This paper reviews technology as well as thermo-mechanical reliability of field programmable gate array (FPGA) IC packaging developed to meet demands of high processing powers. The FPGAs that generally come in CGA/PBGA packages now have more than thousands of solder balls/columns under the package area. These packages need not only to be correctly joined onto printed circuit board (PCB) for interfacing; they also should show adequate system reliability for meeting thermo-mechanical requirements of the electronics hardware application. Such reliability test data are rare or none for harsher environmental applications, especially for CGAs having more than a thousand of columns.
The paper also presents significant test data gathered under thermal cycling and drop testing for high I/O PBGA/CGA packages assembled onto PCBs. Damage and failures of these assemblies after environmental exposures are presented in detail. Understanding the key design parameters and failure mechanisms under thermal and mechanical conditions is critical to developing an approach that will minimize future failures and will enable low-risk insertion of these advanced electronic packages with high processing power and in-field re-programming capability.