bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental and Numerical Study of the Effects of Asymmetric Micro Ratchets on Pool Boiling Performance
Authors: Brumfield Lance , Park Sunggook 
Published: April 2014

Nucleate boiling is an attractive method for achieving high heat flux at low superheat temperatures. It is frequently used for industrial applications such as heat exchangers and is being considered to cool advanced central processing units (CPU) which produce heat fluxes on the order of 1 MW/m2 and are becoming increasingly less efficient to cool via forced conduction of air. The issues with implementing nucleate boiling as a cooling mechanism lies in the difficulty of quantifying the complex and numerous mechanisms which control the process.
A comprehensive nucleate boiling model has yet to be formulated and will be required in order to safely and reliably cool high performance electronics. Spatially periodic systems with localized asymmetric surface structures (ratchets) can induce directed transport of matter (liquid/particles) in the absence of net force. It was hypothesized that ratchets may enhance pool boiling heat transfer by aiding in the removal of vapor which forms on the heated surface. Therefore, experiments on pool boiling using asymmetric micro ratchets of various geometries, with FC-72 as the working fluid, were investigated. Additionally, various numerical pool boiling simulations were performed using FLUENT to better understand the underlying physical principles behind pool boiling.
Effect of Build Orientation on Mechanical Properties of Rapid Prototyping (Fused Deposition Modelling) Made Acrylonitrile Butadiene Styrene (ABS) Parts
Authors: Ashtankar K. M. , Kuthe A. M. , Rathour Bechu Singh 
Published: April 2014

Prototyping is the process of building pre-production models of a product to test various aspects of its design. Fused deposition modeling (FDM) is a process for developing rapid prototype (RP) objects by depositing fused layers of material according to numerically defined cross sectional geometry. The quality of FDM produced parts is significantly affected by various parameters used in the process. This paper aims to study the effect of one such parameter i.e., build orientation, on mechanical properties (mainly tensile and compressive strength) of FDM processed parts. In rapid prototyping (FDM), the orientation of the parts during fabrication is critical as it can affect part strength such as tensile and compressive strength. Specimens are prepared for tensile/compression test as per ASTM standards. It was found that the build orientation of the specimen has more of an impact on strength. The layering build process of rapid prototyping creates a variance in strength depending on the build orientation.
The D695 standard allows for stable compression testing and is used for compression testing. Several geometries are allowed for tension specimens under the D638 standard. We chose the type I specimen as it is the most commonly used and best fit our mechanical testing equipment. From the tensile test result, it is found that when build orientation is increasing from 0° to 90°, ultimate tensile strength decreases. It is maximum at 0° orientation i.e., 15.2 MPa and minimum at 90° orientation i.e., 11.6 MPa. The tensile stress at 0° (i.e. axial direction) is 23.68 % higher than transverse direction (i.e., 90°). From the compressive test results, it is found that, when sample orientation is increasing from 0° to 90°, the ultimate compressive strength decreases. It is maximum at 0° orientation i.e., 26.66 MPa and minimum at 90° orientation i.e., 22.22 MPa. The compressive stress at 0° (i.e. axial direction) is 16.65 % higher than transverse direction (i.e. 90°).
Improved Bed Support for Molecular Sieve Dehydrators and Adsorbers
Authors: Thomas Cyrus R. , Cartwright Gordon T. , Norell Robert G. , Diwakar Philip M. 
Published: April 2014

Adsorbent beds supported by a support grid traditionally use ceramic rope packing to fill an expansion gap between the vessel shell and the bed support grid. This gap allows the bed support grid to move under thermal expansion. The bed support grid would be constricted from thermal expansion without this gap, causing it to buckle or fail during process heating operations. An unobstructed expansion gap is critical for proper performance of the bed support grid. Preventing molecular sieve granules and fines from filling around the rope packing is crucial to long-term bed support performance in molecular sieve dehydrators. Granules and fines converge into an incompressible mass once they are in the expansion gap, preventing bed support grid expansion upon heating. An annular mesh screen or bolted cover plate typically covers the rope packing as the primary sealing mechanism. Nevertheless, gaps between the vessel shell and the annular mesh screen or bolted cover plate allow fines and granules into the expansion gap. Thermally cycled adsorbent beds, such as molecular sieve dehydrators beds, continue to be plagued by bed support grid damage due to the failure of these traditional sealing methods to prevent migration of fines and granules into the expansion gap.
This paper provides details of an improved adsorbent bed support design that utilizes a superior sealing mechanism which features a fixed hold down ring design. The fixed hold down ring design provides an innovative method of sealing the expansion gap that will effectively eliminate the pathway by which molecular sieve granules and fines enter the expansion gap. This is accomplished by welding the hold down ring directly to the vessel shell above the bed support grid. Additionally, the rope packing is moved from the expansion gap to the gap between the hold down ring and the top of the bed support grid. A relief gap is provided in the bottom of the banding around the periphery of the bed support grid to allow expulsion of fines from the expansion gap. These features provide an expansion gap sealing mechanism that eliminates the chronic failures experienced by conventional bed support grid sealing mechanisms. While the fixed hold down ring design has been specifically developed to resolve the thermal expansion issues associated with molecular sieve dehydrators, it can be used for many types of packed beds requiring modified bed support designs.
Wire-Electric Gyroscope
Authors: Avrutov Vadym 
Published: April 2014

The wire-electric gyroscope (WEG) is a new type of the angular rate sensor. The basic principle of the WEG is based on the hypothesis of invariance of the electric current speed for the same wire (coil). It is similar to the Sagnac effect for the speed of light.
The method of angular rate determination is described. The voltage difference between two wire coils with different line coupling can be expressed in applied rotation (angular) rate and velocity of electric current. The scale factor depends on the magnitude of the current, number of the coil turns, the coil’s radius, the cross-section area of the wire and specific (unit) resistance of the wire. WEG can be produced cost-effectively and can be a good choice for low-cost applications.
The Effect of Bench Arrangements on the Natural Ventilation of a Multispan Greenhouse
Authors: Kruger Sunita , Pretorius Leon 
Published: April 2014

In this paper, the influence of various bench arrangements on the microclimate inside a two-span greenhouse is numerically investigated using three-dimensional Computational Fluid Dynamics (CFD) models. Longitudinal and peninsular arrangements are investigated for both leeward and windward opened roof ventilators. The velocity and temperature distributions at plant level (1m) were of particular interest. The research in this paper is an extension of two-dimensional work conducted previously [1]. Results indicate that bench layouts inside the greenhouse have a significant effect on the microclimate at plant level. It was found that vent opening direction (leeward or windward) influences the velocity and temperature distributions at plant level noticeably.
Results also indicated that in general, the leeward facing greenhouses containing either type of bench arrangement exhibit a lower velocity distribution at plant level compared to windward facing greenhouses. The latter type of greenhouses has regions with relatively high velocities at plant level which could cause some concern. The scalar plots indicate that more stagnant areas of low velocity appear for the leeward facing greenhouses. The windward facing greenhouses also display more heterogeneity at plant level as far as temperature is concerned.
Differences Among an Expert and a Non Expert in the Behavior for Chucking in the Lathe
Authors: Sirisuwan Porakoch , Koshino Tetsushi , Narita Chieko , Yoshikawa Takashi 
Published: April 2014

The expert worker (85 years old) has worked for 70 years and the non expert (16 years old) has worked 1 year of experience for the lathe processing. The subjects were compared the difference in the waist, the shoulder and the fore arm movement between the two worker while they were chucking on the lathe machine. Determination used the same parts and the same type of lathe machine for investigated. There were 4 main categories that related three stances position alignment and two hands position on the key chuck.
Using the 6 infrared cameras and 2 video cameras captured the position of each marker. All markers position data which synchronization was taken by a motion analysis system (sampling rate: 100Hz). As a results show the balance movement both the waist and the shoulder during the chucking that had significantly greater in the expert worker than the non expert worker.
Multi-Scale Spatial-Temporal Modelling of 18F-FLT Dynamics and its Relation to 3-Compartment Model
Authors: Liu Dan , Chalkidou Anastasia , Marsden Paul K. , Fenwick John D. 
Published: April 2014

3′-Deoxy-3′-18F-fluorothymidine (18F-FLT) is a radiotracer which accumulates in proliferating cells and is used for positron emission tomography (PET) imaging. This study investigates the heterogeneous transport and uptake of FLT in tumors, aiming to understand the links between FLT dynamics described by a mechanistic spatial-temporal model and by a simplified 3-compartment model, and to study the validity of the compartment model.
In the proposed multi-scale spatial-temporal model, the tumor consists of vasculature, interstitium and tumor cells. The heterogeneous spatial-temporal distribution of FLT is determined by a convection-diffusion-reaction equation, numerically solved using the finite difference method (FDM). Physiological parameters were collated from the literature and used as model coefficients, and vascular maps were created based on histological micro-vascular density (MVD). Results show that the multi-scale model can generate FLT time activity curves (TACs) similar to TACs derived from clinical PET images. And so long as the region of interest (ROI) is a near-closed system, a 3-compartment model can recover reasonable estimates of averaged FLT dynamics.
Dynamic Modeling, Simulation and Exergy Analysis of an Innovative Hydronic Heating System
Authors: Sangi R. , Streblow R. , Müller Dirk 
Published: April 2014

In this study, dynamic modeling and simulation of a decentralized hydronic heating system has been performed. The simulated space heating system is a model of an innovative heating system of an apartment with a boiler that supplies heat for eight radiators which are served by distribution pipes. Eight small pumps, located at the outlet of the radiators instead of a central circulation pump, work according to demand, and supply each radiator with hot water only when required. A PID controller regulates the rotational speed of the pumps and consequently the power of the radiators to maintain the room temperature at the set point.
To evaluate the performance of such a heating system, a model of the entire energy chain from generation to distribution is needed. Therefore, in this work, detailed sub-models for the hydraulic system have been developed and coupled with the model of a building to make a general model for simulating the performance of the whole system. The analysis has been carried out by simulation of the system using the object-oriented programing language Modelica. Dymola, which is a multi-domain modeling and simulation tool, has been used as simulation environment. The Modelica Standard Library 3.2 and the Modelica libraries for building simulation such as BaseLib, Database, Building and HVAC components libraries have been applied to simulate the hydraulic and thermal behavior of the system. In the next step, the system has been analyzed form exergy point of view and the simulation results from the dynamic model have been presented in an exergetic framework.
Engineering Decision Making in an Open Age
Authors: Fukuda Shuichi 
Published: April 2014

In an age of diversification and changes, a new framework for decision making for a team is required. As growing complexity and diversification call for team members from a wide variety of areas, a decision cannot be made one-time as it used to be and it must be reached by trials and errors step by step. Such dynamic decision making has to convince members at each step by providing different perspectives for each member to understand the line of reasoning, and must allow lazy evaluation, because some members cannot understand what pieces of knowledge and experience are called for until later step, when clearer perspective is available. Steps proceed by satisfying at least one member. If it fails, then it backtracks to the previous step until it satisfies one more member. This process is repeated until all members are satisfied.
Artificial Intelligence allows such trial and error decision making to make all members feel satisfied. The usefulness of this approach is demonstrated by applying developed WPS producing tool to many applications in industry.
And it is believed this DDM tool will be very useful for decision making in other areas, too, where systems are very complex and diverse.
Mechanical Design and Students’ Creativity: “Think Outside the Box”
Authors: Mokhtar Wael 
Published: April 2014

A design project was used in junior level mechanical design course to challenge the students’ creativity skills. Beside the theoretical foundation of the course subject, the students were introduced to several professional skills such as: decision making tools, technical review meetings, interaction with customers, and teamwork skills. The design challenge was to develop a bike rack to meet a list of technical and marketing constraints. Details of the project requirements are presented with a brief overview of the main project mentoring tools. Students’ creativity is discussed through two samples of the student work.
It was noticed that, the basic creativity skills of the students can be improved by using some of the training tools, however, the students vary in their response to this training.
An Experimental Investigation of a Temperature Controlled Vapor Supply System
Authors: Ryan Robert G. , Bunting Jeffrey 
Published: April 2014

A variety of applications require a constant pressure vapor supply for processes such as purging fluid systems. A typical design would use a high pressure tank of gas (e.g. helium) along with a mechanical pressure regulator to deliver a constant pressure flow. An alternative concept for the vapor source is to use a tank containing a saturated liquid-vapor mixture. As the vapor is drawn off of the top of the tank, the temperature of the mixture is controlled to maintain the desired vapor delivery pressure. The potential advantage of this approach is that the vapor supply system can be designed to be lighter, more compact, and safer.
An experiment was designed to test the practicality of this concept in a small scale system. Carbon dioxide was chosen for the saturated mixture due to its availability, safety, and desirable operating pressures near ambient temperature levels. The apparatus was designed to allow for the measurement of relevant temperatures and pressures over a range of vapor delivery flow rates. Temperature control of the supply tank was accomplished by submergence in an ice bath. The experimental results confirm that this type of system can produce a well regulated vapor supply at low flow rates, but fails to produce steady pressures at higher delivery flows due to limitations of the heat transfer process in the supply tank.
Analysis of the Possibility of Water Induction in Turbine From Direct Contact Water Heater at Load Shedding Power
Authors: Gotovsky M. A. , Ermolov V. F. , Mikhailov V. E. , Sukhorukov Yu. G. , Trifonov N. N. 
Published: April 2014

Direct-contact heaters of feed water are especially popular as low-pressure heaters (LPH). These devices are successfully used in Russia during a long time both for conventional and nuclear power plants. Moreover, abilities of such devices to operate as deaerators led to the development deaeratorless schemes. One of most important conditions of reliable operating of such LPH is the prevention of damage of steam turbines, because of back flow of wet steam to the turbine. In this paper processes of boiling up are considered in direct contact LPH-2 which occur during stopping of turbine and its specific features concerned with dependence of sonic speed two-phase flow on vapor and liquid volumetric portions during flow enter in compensating tubes. Computer analysis showed, that the rate of generation of steam in the superheated water depends on the pressure exceptionally strong.
Zone of churn flow regime, which is formed in the upper part of the condensate tank appears very sensitive instrument of flow rate control. As it is shown in such a situation, the system becomes self-governing and will not miss a steam consumption, which leads to the entrance some part of churn regime zone to pressure equalizing tubes. The calculations show that the safety can be ensure even in the conditions when backpressure valve absent. Such the conclusion is confirmed by the experience on operation direct contact LPH in Russian power plants.
Test Apparatus for Powered Saw Chain Systems
Authors: Otto Andrew W. , Parmigiani John P. 
Published: April 2014

The emergence of battery operated landscaping equipment has driven increased scrutiny of the energy usage of such devices. Energy consumption is a primary design constraint for these new yard tools due to the low energy density of current battery technology compared to gasoline. Consumer battery-powered electric chain saws are an example. In order to provide both portability and usability the system’s power use must be understood in detail. Power use associated with cutting, friction, vibration, chip removal, and parasitic loads are all relevant entities in cutting system design. Interface friction between the cutting chain and bar as well as increases in cutting force due to chain vibration are of particular interest.
In this work, a test apparatus capable of determining the efficiency of cutting systems for use on chain saws is designed and constructed. Cutting power and frictional losses can be determined with the device under automated, user specified conditions. Operational parameters including chain velocity, feed velocity, and feed load may be used as feedback for device control. A universal mounting and drive system allows for testing with a wide range of off-the-shelf chains, bars, and drive sprockets. Input torque to the chain and reaction forces on the cutting media are recorded outputs which are used to analyze system efficiency. Preliminary work with the machine confirms trends found in existing research literature. Future research performed with the test apparatus will aid in new product design and enhance understanding of energy consumption in chainsaw cutting systems.
Innovative Designs for the Suspension System of Horizontal-Axis Washing Machines: Secondary Suspensions and Tuned Mass Dampers
Authors: Argentini T. , Belloli M. , Robustelli F. C. , Martegani L. , Fraternale G. 
Published: April 2014

Cabinet vibrations during spinning cycles of washing machines are often perceived negatively by customers, both in acoustic and visual terms. Therefore, in a market that is more and more oriented towards customer satisfaction and appliance efficiency, reducing cabinet vibrations and noise is a very attractive target.
Previous experimental campaigns have highlighted that currently installed dry-friction dampers have highly non-linear characteristics and they are the main source of broadband forcing on the cabinet panels. To overcome these negative effects, two innovative designs for the suspension system have been studied and are here presented: the first solution is a secondary suspension system, designed to filter out the high frequency force components introduced by the dampers and therefore to mitigate panel vibrations; the second solution is more radical and it consists in removing the existing dampers and to substitute them with a tuned mass damper (TMD), directly fixed to the oscillating group. These solutions are a compromise between cost and efficiency, since a linear oil damper would impact excessively on the final cost of the appliance.
The secondary suspension system has been designed to meet the very strict requirements of the manufacturer: low cost (which implies small mass) and applicable to the existing machine without any modification of any part other than the dampers themselves. The desired results have been achieved increasing the mass of the damper rod and introducing a fixed-fixed (or hinged-hinged) beam spring. The prototype of the secondary suspension has been tested independently and assembled in the washing machine, and the vibratory and acoustic results will be reported.
The introduction of a TMD and the contextual removal of the dry-friction dampers, on the contrary, requires the modification of the oscillating group in order to work efficiently. As a matter of fact, a principle for the design of oscillating groups is the space optimization, which usually leads to asymmetric distributions of mass of the oscillating group, that in their turn lead to asymmetrically coupled mode shapes. This dynamic characteristic does not suit the design of a simple and compact TMD, with a limited number of degrees of freedom. We show that careful mass distribution and a specifically designed 2-dofs TMD can efficiently substitute the original dampers. An elemental prototype of the so defined TMD has been tested on a shaking table, and it seems an effective alternative to classical suspension systems.