bluuebunny/crossref_metadata_2025 huggingface dataset:
Mexico Redux
Authors: Brown Alan S.
Published: July 2018

This article discusses formerly America’s top low-cost manufacturer; the neighbor to the south is repositioning itself to be an advanced industrial player. Colantuoni manages market research for Mexico’s Offshore Group, which develops maquiladoras for firms that want to manufacture in Mexico. Maquiladoras import goods from the United States without paying taxes or tariffs, manufacture or assemble them into products, and export them back across the border. Today, Mexico is making more complex and sophisticated products, as well as goods that require fast turnarounds and customization. It has used its advantages to retain business even in industries—computers, telecommunications, and appliances—that seemed a natural fit for China. Management in general is also a consideration for manufacturers. Mexico’s physical proximity to the Unites States and Canada, and the shared business culture of North America make management easier. In many ways, competition from China has been good for Mexico. It has spurred it to move into engineering and manufacturing higher value-added products.
Building Trust
Authors: Doucet Mia
Published: July 2018

This article focuses on the essentials of doing business with China that can be developed only over the long haul. China is a big country and, apparently, it is especially difficult to police intellectual property infractions at the local level. Rather than waiting for Beijing's policy to trickle down to local government, a company can take its own precautions to protect proprietary technology. This starts with looking deep within the fiber of Chinese society to understand why IP problems occur. People with international degrees are more aware of acceptable Western business practices. It is an advantage to hire right out of school, so that you can instill your own company’s values rather than inherit the work practices of others. Pay employees well, so they have a strong economic incentive to remain loyal. Women are often overlooked for all the reasons they were once devalued in Western culture. Yet the consensus among Westerners who teach in China is that the women are focused and work hard.
Make No Mistake
Authors: Thilmany Jean
Published: July 2018

This paper explains the concept of goof-proofing and its usefulness in engineering design. No standard design rules exist for engineers to follow in anticipation of human error. Human reliability analysis tools such as event trees and fault trees to model a human's contribution to events such as decreasing one's speed on an exit ramp. To minimize human error, engineering students color code wires and use specific prong configurations in the design of an automobile. It is observed that engineers follow failure modes and effects analysis procedures. The failure modes procedure isolates potential failures within a system or product. Effects analysis is the study of the consequences of those failures. The attitude on the part of designers is that they have the requisite knowledge, either from past projects or due to their expertise. The paper concludes that regardless of how engineers go about goof-proofing their designs, they must keep the end user in mind.
Quality Control
Authors: Doucet Mia
Published: July 2018

This review emphasizes on the importance of communication between business performing parties. According to a survey, many business owners who work with mainland Chinese suppliers report that consistent quality is their biggest challenge. The biggest challenge in doing business in China is quality, reliability, and delivery. The survey shows that though the cost is quite low, but that is part of the problem. Companies are constantly being disappointed by their Chinese suppliers because they are taking shortcuts that have not been approved to save money. This has resulted in product yield loss and reliability problems. According to an application engineer, most Westerners think that most Asians speak English, which is a big misunderstanding. The person who works in overseas marketing does, but the engineers and quality control people do not. Westerners make their presentations, unaware they are not being understood 100%. Asians have a lot of ideas, but it is hard to explain over the language barrier.
Engineering our Favorite Pastime
Authors: Smith Lloyd , Sherwood James
Published: July 2018

This article describes the equipment and technology advances in baseball and softball games. Research efforts are currently being pursued by the authors to develop a layer-by-layer finite element model of a baseball. While work on improved ball models is ongoing, a number of significant accomplishments have been made with current models. These include comparing bat performance, describing the plastic deformation (denting) observed in metal bats, and the failure modes observed with wood bats. To simulate the bat/ball impact at game-like speeds, a durability machine is used to fire balls at a bat at speeds up to 200 mph, at the rate of 10 per minute. After a ball is shot, it falls into a trough and is loaded back into the magazine, which holds up to 36 balls. The bat-support mechanism simulates the grip and flexibility of a batter and can be programmed to rotate the bat between hits to simulate the use of hollow bats or to remain “label up” as is needed for wood bats.
Mapping Competencies
Authors: Ranade Saidas , Tamara Cassio , Castiblanco Edgar , Serna Anibal
Published: July 2018

This article discusses the experience of a company in applying a visual method to determine the abilities of its engineers. Ecopetrol, one of South America’s largest energy enterprises, embarked on a process known as competency mapping. This term is often applied to identify the soft skills or behaviors that make employees effective in their roles and distinguish some as candidates for leadership positions. In Ecopetrol’s case, the competencies to be mapped were the objective skills that engineers require to deal successfully with the daily operations of a refinery. This project gave the company insights into the skills of its engineers. A side-by-side comparison of the Knowledge-Capability maps for different engineering disciplines revealed that almost 30 competencies were common among the various engineering disciplines. These competencies included information technology skills such as ability to use Microsoft Office and tools for capturing real time data, technical foundational competencies such as working knowledge of probability and statistical analysis, ability to use various company documents, and business competencies such as knowing Ecopetrol’s key performance indicators.
The Unwritten Laws of Engineering
Authors: King W. J. , Skakoon James G.
Published: July 2018

This article presents an overview of several topics discussed in the Unwritten Laws of Engineering publication. The article also highlights that executives should have their business organized so that they could be away on business or vacation at any time and still have everything move along smoothly. The faculty for reducing apparently complicated situations to their basic, essential elements is a form of wisdom that must usually be derived from experience. It is critical to make sure that all activities and all individuals are supervised by someone competent in the subject matter involved. Experts advise that matrix management considerably leverages knowledge and skills, opening opportunities for employees to branch out from their usual offices and disciplines. One of the most serious responsibilities of managers is to review the performance of their subordinates. An important part of the job of developing engineers is to furnish them with ample background knowledge and, as a rule, this involves a certain amount of travel.
Power Window
Authors: Winters Jeffrey
Published: July 2018

This article analyzes the energy identity crisis in some oil-producing countries. It highlights that the retail price for gasoline in countries such as Libya, Saudi Arabia, Bahrain, and Yemen was at or below the cost on the world market of the petroleum needed to produce it. However, Egypt went from an exporter of more than 300,000 barrels of oil a day in 1999 to a net importer beginning in 2009. And as a consequence, the prices for gasoline in Egypt went from below the raw material cost in 2006 to being comparable to those in the United States. Tunisia shifted from an exporter to an importer in 2000. Thanks to strong consumption growth, Bahrain has also seen its exports plummet from more than 30,000 barrels a day in the 1990s to around 3500 today. The Saudi consumption curve is climbing at about 4% per year, and unless the country can raise production above 11 million barrels a day, its exports will disappear by 2050.
Project: Crowdsourcing
Authors: Falcioni John G.
Published: July 2018

This article discusses the contribution of readers in creating the feature content of an entire issue of Mechanical Engineering magazine. The only parameter to this project was that the ideas for articles be focused on at least one of ASME’s three strategic initiatives. That is, they should relate to energy, engineering workforce development, or global impact and outreach. The project started by spreading the word about the initiative. Over the course, the editors solicited readers’ input, streamlined their comments and suggestions, presented readers with a list of ideas they had submitted, and then asked the readers to vote on them. Two ideas from each of the three ASME strategic areas were used. Writers were identified who would bring the most interesting perspectives to each of the topics, and then those writers were asked to write essays. The result of the 12-month process was the first crowdsourced issue of the magazine.
The World is More Than Complicated
Authors: Noor Ahmed K.
Published: July 2018

This article discusses the need of complex systems to be adaptive, and various innovative technologies that are required to engineer these systems. Complex adaptive systems consist of several simultaneously interacting parts or components, which are expected to function in an uncertain, complex environment, and to adapt to unforeseeable contingencies. The defining characteristics of complex adaptive systems are that the components are continually changing, the systems involve many interactions among components, and configurations cannot be fully determined in advance. Studies have shown that complex systems of the future will require a multidisciplinary framework—an approach that has been called emergent (complexity) engineering. Emergent engineering designs a system from the bottom-up by designing the individual components and their interactions that can lead to a desired global response. Although significant effort has been devoted to understanding complexity in natural and engineered systems, the research into complex adaptive systems is fragmented and is largely focused on specific examples. In order to accelerate the development of future diverse complex systems, there is a profound need for developing the new multidisciplinary framework of emergent engineering, along with associated systematic approaches, and generally valid methods and tools for high-fidelity simulations of the collective emergent behavior of these systems.
An EKG in your Underwear
Authors: Varadan Vijay K.
Published: July 2018

This article discusses the use and benefits of e-Nanoflex that combines nanostructured sensors, smart phones, and cloud computing and promises a new platform for everyday medical monitoring. At the University of Arkansas, a team of surgeons, engineers, and computer scientists has developed a personal heart monitor based on e-Nanoflex nanostructured sensors. The sensors can be embedded in clothing that can be worn and washed just like any other garment. The e-Nanoflex can also monitor recovery from surgery, medical compliance, and neurological diseases, or help athletes optimize their training routines. The nanostructured sensors developed at the University of Arkansas make true portable, wearable electrocardiograph (EKG) systems possible. They consist of tiny metal nanowires growing outwards from the surface of the electrodes. Sophisticated software can monitor data from e-Nanoflex sensors about heart rate consistency and other factors to ensure that patients comply with their prescriptions. The combination of wearable nanostructured sensors, smart phones, and cloud computing makes wearable EKGs possible.
Cogeneration: Gas Turbine Multitasking
Authors: Langston Lee S.
Published: July 2018

This article describes the functioning of the gas turbine cogeneration power plant at the University of Connecticut (UConn) in Storrs. This 25-MW power plant serves the 18,000 students’ campus. It has been in operation since 2006 and is expected to save the University $180M in energy costs over its 40-year design life. The heart of the UConn cogeneration plant consists of three 7-MW Solar Taurus gas turbines burning natural gas, with fuel oil as a backup. These drive water-cooled generators to produce up to 20–24 MW of electrical power distributed throughout the campus. Gas turbine exhaust heat is used to generate up to 200,000 pounds per hour of steam in heat recovery steam generators (HRSGs). The HRSGs provide high-pressure steam to power a 4.6-MW steam turbine generator set for more electrical power and low-pressure steam for campus heating. The waste heat from the steam turbine contained in low-pressure turbine exhaust steam is combined with the HRSG low-pressure steam output for campus heating.
Nature's Nanotechnology
Authors: Bhushan Bharat
Published: July 2018

This article presents an overview of the emerging field of biomimetics. Biomimetics is highly interdisciplinary and is gaining a foothold in the scientific and technical arena. Biomimetics involves the understanding of biological functions, structures, and principles of various objects found in nature by biologists, physicists, chemists, and material scientists, and the design and fabrication of various materials and devices of commercial interest from bioinspiration. Today, biomimetic materials are moving out of the laboratory and into industrial applications. Significant advancements in nanofabrication allow engineers to replicate structures of interest in biomimetics using smart materials. The commercial applications include nanomaterials, nanodevices, and processes that may enable self-cleaning surfaces or pads that hang pictures without hooks or wires. Some of these applications may at first seem magical, but they simply are the result of applying science and engineering to uncovering the secrets of nature.
The Winning Résumé
Authors: Friesen E.N.
Published: July 2018

This article discusses how one can make a successful résumé. Creating a successful résumé requires that you know yourself and document that knowledge effectively. A good résumé is needed to make your case to someone who has the authority to hire you. To improve your chances of getting ahead, you want more than a good résumé. Start and maintain a daily diary or record of events and what you have decided and done. Analyze and assess, correct, execute, and then identify the critical few activities and events of significance to your career and work history. Your log will provide you with a permanent record of what you were doing and thinking each day, along with your notes and observations on what happened of interest, along with who was involved. For construction work and projects, it is good to note the weather conditions, along with working conditions, crew deployments, and accomplishments. Compile your significant achievements at least monthly in a summary document. You will benefit by reviewing your daily record and making a concise summation.
Drawn to Bigger Things
Authors: Woods Robert O.
Published: July 2018

This article outlines the history of wire drawing technology. The origin of wire drawing tools has been traced to well before 2000 BC era. The earliest examples are found in Egypt where gold wire was drawn to make jewelry. Anywhere in the spectrum between making jewelry and building bridges, the work starts with an elongated metal billet, which has been shaped by hand working or machine rolling. One end is reduced to a diameter that will pass through a funnel-shaped die, which is typically circular although it is possible to extrude other cross-sections. The small end of the billet is pulled (“drawn”), forcing the metal to be elongated and reduced in diameter. Drawing usually takes place in several steps, and the product can be variously treated between stages. This might involve softening or plating. Lubricants are applied in almost every case although very ductile metals such as gold were drawn without lubrication, sometimes through holes in gemstones.
Things Happen
Authors: Petroski Henry
Published: July 2018

This article presents various excerpts from a book To Forgive Design: Understanding Failure, by Henri Petroski. The book focuses on inevitability of failure and the role it plays in the advance of technology. Technology has always been risky business, but quantifying that risk is a relatively new phenomenon in the worlds of engineering and management, which should be more integrated than they often are. Parking decks are familiar structures that do fail now and then, and the failures can often be traced to something out of the ordinary in their design or construction. Such collapses might never have occurred if the structures and everything surrounding them had been exact copies of those that had stood the test of time, but even repeated success is no guarantee against future failure. In fact, prolonged success, whether it be in a space shuttle program or in the design and construction of parking garages, tends to lead to either complacency or change, both of which can ultimately lead to failure.
Knocking the NOx out of Biodiesel
Authors: Houlihan Thomas
Published: July 2018

This article describes various experimental demonstrations to show the benefits of using biodiesel fuels to reduce emissions caused by NOx. Biodiesel fuel blends deliver benefits in reduced engine emissions of particulate matter. NOx emissions are precursors in the formation of smog and acid rain. By achieving NOx neutrality, emulsified biodiesel fuel allows the full benefits of a biofuel to be realized. The introduction of water into the combustion process by the utilization of emulsified fuels results in the generation of triple benefits—the reduction in emissions of NOx, particulate matter, and greenhouse gases. These results suggest that emulsified fuel technology is an effective and cost beneficial emission-reduction technology. It is readily available to accommodate future requirements for hydrocarbon emissions and greenhouse gas emissions reductions. Considering the number of trucks, trains, and other diesel-powered vehicles in use, biodiesel fuels have the potential to make a significant contribution to improving both the air quality and perhaps the national economy of the United States.
Blade Tips - Clearance and Its Control
Authors: Langston Lee S.
Published: July 2018

This article focuses on studying blade tip clearance phenomena. It is important to realize that to be freely turning, a blade (or a cantilevered stator) must have a clearance gap between its tip and the engine casing (or hub). Such clearances introduce aerodynamic losses, decreasing gas turbine efficiency. Tip leakage losses in compressors can be significant and have been reviewed by the experts. During transient operations, gas turbine blade tip clearances will change based on blade/disk centrifugal loads and the different response times of engine parts to thermally induced expansions and contractions. Designers have perfected active clearance control (ACC) systems to deal with these transient conditions. ACC uses cool or hot gas path and fan air at appropriate times during transients to control the rate of expansion or contraction of internal parts adjacent to the gas path and outer casings. The research shows that continued enhancement of blade tip clearance management systems over a range of engine operating conditions has brought and will bring about gains in gas turbine efficiency.
Detonation Gas Turbines
Authors: Langston Lee S.
Published: July 2018

This article focuses on various technical and functional aspects of detonation gas turbines. Detonation combustion involves a supersonic flow, with the chemical reaction front accelerating, driving a shock wave system in its advancement. In the 1990s, detonation-based power concepts began with pulse detonation engines (PDEs), and have now moved into the continuous detonation mode, termed rotating detonation engines (RDEs). Modern gas turbine combustors are compact, robust, tolerant of a wide variety of fuels, and provide the highest combustion intensities. The single-spool RDE gas turbine is represented by a detonation cycle, which accounts for the supersonic features of the heat addition, starting at station 2.5′. Continued research and development by the RDE technical community is needed to see if the promise of improved performance and downsized turbomachinery for a detonation cycle is real.
Engineers in the Distance
Authors: Gibson Tom
Published: July 2018

This article presents views of Todd Torrence on introduction of online learning programs that can open paths from technical to technological. The University of North Dakota, which offers the only accredited online BSME program in the United States, is in a state where hydraulic fracturing has sharply increased oil production. The university has applied for accreditation of an online program offering a Bachelor of Science in Petroleum Engineering. The UND online BSME program covers the same material as its on-campus counterpart. North Carolina State has a 2+2 program where a student can go to a partnering university at the east and west ends of the state for the first two years of their undergraduate work. The University of North Dakota online BSME program covers the same material as its on-campus counterpart. Part of the accreditation process is assuring that the online degree is equivalent to the face-to-face degree. The challenge with undergrad online engineering programs is their sheer size and the time it takes to complete them, as compared with graduate programs.
Nuclear's Next 40 Years
Authors: Snyder Barbara R. , Meyer Theodore A. , Balkey Kenneth R.
Published: July 2018

This article highlights the efforts that need to be put in order to maintain and build nuclear power plants to ensure a reliable source of electric generation. With increasing carbon restrictions and the growing demand for electricity, reliable, carbon-free baseload electricity generation is more important than ever for the United States. The pertinent ASME Section XI Boiler and Pressure Vessel Code requirements were modified to support license renewal. Similar steps, plus the development of new solutions for emerging aging issues, will need to be applied for second license renewals, extending the operating life of these reactors to 80 years. Industry resources must commit to demonstrate the necessary understanding of any significant changes in aging issues beyond 60 years. It is important that industry bodies, such as the Electric Power Research Institute and utility owner’s groups, and suppliers – along with the individual utilities and plants that are the leading candidates for operation beyond 60 years – collectively assure themselves and the U.S. NRC that the pertinent aging issues are identified and appropriate aging management methods are defined or created.
Rare Earth Elements in North Dakota Lignite Coal and Lignite-Related Materials
Authors: Laudal Daniel A. , Benson Steven A. , Palo Daniel , Addleman Raymond Shane
Published: July 2018

Rare earth elements (REE) are crucial materials in an incredible array of consumer goods, energy system components, and military defense applications. However, the global production and entire value chain for REE is dominated by China, with the U.S. currently 100% import reliant for these critical materials. Traditional mineral ores including those previously mined in the U.S., however, have several challenges. Chief among these is that the content of the most critical and valuable of the rare earths is deficient, making mining uneconomical. Further, the supply of these most critical rare earths is nearly 100% produced in China from a single resource that is only projected to last another 10–20 years. The U.S. currently considers the rare earths market an issue of national security. It is imperative that alternative domestic sources of rare earths be identified and methods developed to produce them. Recently, coal and coal byproducts have been identified as one of these promising alternative resources. This paper details the results of a study on characterization of North Dakota lignite and lignite-related feedstocks as an assessment of their feasibility for REE recovery. The abundance, distribution, and modes of occurrence of the REE in the samples collected were determined in this initial study to inform the selection of appropriate extraction and concentration methods to recover the REE. Materials investigated include the lignite coals, clay-rich sediments associated with the coal seams, and materials associated with a lignite beneficiation system and power plant. The results show that high REE levels exist both in lignite coals and associated sediments. The form of the REE in the clay materials is primarily as ultrafine mineral grains. In the lignite coals, approximately 80–95% of the rare earths content is organically associated, primarily as coordination complexes.
Combustion Mode Switching Characteristics of a Medium-Duty Engine Operated in Compression Ignition/PCCI Combustion Modes
Authors: Singh Akhilendra Pratap , Bajpai Nikhil , Agarwal Avinash Kumar
Published: July 2018

Premixed charge compression ignition (PCCI) combustion is a novel combustion concept, which reduces oxides of nitrogen (NOx) and particulate matter (PM) emissions simultaneously. However, PCCI combustion cannot be implemented in commercial engines due to its handicap in operating at high engine loads. This study is focused on the development of hybrid combustion engine in which engine can be operated in both combustion modes, namely, PCCI and compression ignition (CI). Up to medium loads, engine was operated in PCCI combustion and at higher loads, the engine control unit (ECU) automatically switched the engine operation to CI combustion mode. These combustion modes can be automatically switched by varying the fuel injection parameters and exhaust gas recirculation (EGR) by an open ECU. The experiments were carried out at constant engine speed (1500 rpm) and the load was varied from idling to full load (5.5 bar brake mean effective pressure (BMEP)). To investigate the emission and particulate characteristics during different combustion modes and mode switching, continuous sampling of the exhaust gas was done for a 300 s cycle, which was specifically designed for this study. Results showed that PCCI combustion resulted in significantly lower NOx and PM emissions compared to the CI combustion. Lower exhaust gas temperature (EGT) in the PCCI combustion mode resulted in slightly inferior engine performance. Slightly higher concentration of unregulated emission species such as sulfur dioxide (SO2) and formaldehyde (HCHO) in PCCI combustion mode was another important observation from this study. Lower concentration of aromatic compounds in PCCI combustion compared to CI combustion reflected relatively lower toxicity of the exhaust gas. Particulate number-size distribution showed that most particulates emitted in PCCI combustion mode were in the accumulation mode particle (AMP) size range, however, CI combustion emitted relatively smaller sized particles, which were more harmful to the human health. Overall, this study indicated that mode switching has significant potential for application of PCCI combustion mode in production grade engines for automotive sector, which would result in relatively cleaner engine exhaust compared to CI combustion mode engines.
Evaluation of Fuel Injection Strategies for Biodiesel-Fueled CRDI Engine Development and Particulate Studies
Authors: Singh Akhilendra Pratap , Agarwal Avinash Kumar
Published: July 2018

Fuel injection parameters such as fuel injection pressure (FIP) and start of main injection (SoMI) timings significantly affect the performance and emission characteristics of a common rail direct injection (CRDI) diesel engine. In this study, a state-of-the-art single cylinder research engine was used to investigate the effects of fuel injection parameters on combustion, performance, emission characteristics, and particulates and their morphology. The experiments were carried out at three FIPs (400, 700, and 1000 bar) and four SoMI timings (4 deg, 6 deg, 8 deg, and 10 deg bTDC) for biodiesel blends [B20 (20% v/v biodiesel and 80% v/v diesel) and B40 (40% v/v biodiesel and 60% v/v diesel)] compared to baseline mineral diesel. The experiments were performed at a constant engine speed (1500 rpm), without pilot injection and exhaust gas recirculation (EGR). The experimental results showed that FIP and SoMI timings affected the in-cylinder pressure and the heat release rate (HRR), significantly. At higher FIPs, the biodiesel blends resulted in slightly higher rate of pressure rise (RoPR) and combustion noise compared to baseline mineral diesel. All the test fuels showed relatively shorter combustion duration at higher FIPs and advanced SoMI timings. The biodiesel blends showed slightly higher NOx and smoke opacity compared to baseline mineral diesel. Lower particulate number concentration at higher FIPs was observed for all the test fuels. However, biodiesel blends showed emission of relatively higher number of particulates compared to baseline mineral diesel. Significantly lower trace metals in the particulates emitted from biodiesel blend fueled engine was an important finding of this study. The particulate morphology showed relatively smaller number of primary particles in particulate clusters from biodiesel exhaust, which resulted in relatively lower toxicity, rendering biodiesel to be more environmentally benign.
Modulating Band Gap Structure by Parametric Excitations
Authors: Yang Xiao-Dong , Cui Qing-Dian , Qian Ying-Jing , Zhang Wei , Lim C. W.
Published: July 2018

Artificial periodic structures are used to control spatial and spectral properties of acoustic or elastic waves. The ability to exploit band gap structure creatively develops a new route to achieve excellently manipulated wave properties. In this study, we introduce a paradigm for a type of real-time band gap modulation technique based on parametric excitations. The longitudinal wave of one-dimensional (1D) spring-mass systems that undergo transverse periodic vibrations is investigated, in which the high-frequency vibration modes are considered as parametric excitation to provide pseudo-stiffness to the longitudinal elastic wave in the propagating direction. Both analytical and numerical methods are used to elucidate the versatility and efficiency of the proposed real-time dynamic modulating technique.
Integration of Statistics- and Physics-Based Methods—A Feasibility Study on Accurate System Reliability Prediction
Authors: Hu Zhengwei , Du Xiaoping
Published: July 2018

Component reliability can be estimated by either statistics-based methods with data or physics-based methods with models. Both types of methods are usually independently applied, making it difficult to estimate the joint probability density of component states, which is a necessity for an accurate system reliability prediction. The objective of this study is to investigate the feasibility of integrating statistics- and physics-based methods for system reliability analysis. The proposed method employs the first-order reliability method (FORM) directly for a component whose reliability is estimated by a physics-based method. For a component whose reliability is estimated by a statistics-based method, the proposed method applies a supervised learning strategy through support vector machines (SVM) to infer a linear limit-state function that reveals the relationship between component states and basic random variables. With the integration of statistics- and physics-based methods, the limit-state functions of all the components in the system will then be available. As a result, it is possible to predict the system reliability accurately with all the limit-state functions obtained from both statistics- and physics-based reliability methods.
Experimental and Modeling Study on Solar System Using Linear Fresnel Lens and Thermoelectric Module
Authors: Köysal Yavuz , Özdemir Ali Ekber , Atalay Tahsin
Published: July 2018

This work is concerned with an experimental design for generating power from thermoelectric generator (TEG) and linear Fresnel lens collector with one-axis solar tracking system. Main purpose of this experimental design is to measure the performance of the TEG with linear Fresnel lens collector. This work also aims to create a mathematical model by using adaptive neuro fuzzy inference system (ANFIS) model so that the electrical production estimates of the constructed system can be made for a given data set. For this reason, two individual systems, selective surface adapted for achieving medium temperature scale and nonselective surface for low temperatures, were constructed. There are two different coolant systems, which are passive and active, to create effective open circuit voltage values. Experimental results show that the maximum open circuit voltages were obtained as 0.442 V and 1.413 V for experimental system with selective surface adapted, as 0.341 V and 0.942 V with nonselective surface adapted when the received radiated power on Fresnel lens was measured nearly 625 W/m2 on average in the noon time. Experimental values were collected for the selective surface adapted system on 11th and 12th of September, 2017 and for nonselective surface on 13th of September, 2017, respectively, in Samsun/Turkey with location 41°14′N and 36°26′E. The collected data such as solar irradiation, wind speed, ambiance temperature, and open circuit voltage were used for (ANFIS) modeling. Obtained result shows that experimental calculations and modeling are consistent with each other.
Experimental and Numerical Investigations of Closed Radial Inflow Turbine With Labyrinth Seals
Authors: Li Wen , Wang Xing , Zhang Xuehui , Zhang Xinjing , Zhu Yangli , Chen Haisheng
Published: July 2018

It is a common practice to use closed impeller in radial inflow turbine against the flow leakage from tip clearance of impellers, especially in small volume flow condition. It utilizes labyrinths between the shroud and the case to abate the higher pressure leakage. Experimental and computational investigations of shroud clearance flow in a radial inflow turbine with labyrinth seals are presented in this paper. Compared with the result without leakage, numerical computation result including the leakage of labyrinth seals agrees better with that of the experiment result, which indicates that the leakage of labyrinth seals cannot be neglected. Several geometrical arrangements with a series of different clearance of labyrinth seals are investigated experimentally and numerically, and the dimensionless shroud clearance is of 0%, 0.6%, 1.2%, 1.8%, 2.7%, 3.6%. Finally, the character of flow and loss is analyzed by computational fluid dynamics (CFD) tools. The results indicate that the labyrinth seal flow has no effect on the main flow passage and mainly causes different leakage mass flow.
Stability Enhancement With Self-Recirculating Injection in Axial Flow Compressor
Authors: Li Jichao , Du Juan , Li Zhiyuan , Lin Feng
Published: July 2018

Self-recirculating injection, which bleeds air from the downstream duct of the last blade row and injects air as a wall jet upstream of the first rotor blade row, is experimentally investigated after the design of its structure in single- and three-stage axial flow compressors. External injection and outlet bleed air are selected for comparison. Results show that self-recirculating injection can improve the stall margin by 13.67% and 13% on the premise of no efficiency penalty in single- and three-stage axial flow compressors with only 0.7% and 4.2% of the total injected momentum ratio recirculated near stall, respectively. The self-recirculating injection is the best among all the three cases if the influence on pressure rise coefficient and efficiency is comprehensively considered. Moreover, findings indicate that the upstream injection plays an important role in terms of stability-enhancement. The details of the flow field are captured using a collection of pressure transducers on the casing with circumferential and chordwise spatial resolution. A detailed comparative analysis of the endwall flow indicates that the self-recirculating injection can postpone the occurrence of stalling in the proposed compressor by delaying the forward movement of the interface between the tip leakage flow (TLF) and main stream flow (MF), weakening the unsteadiness of TLF (UTLF), and sharply decreasing the circumferentially propagating speed dominated by the UTLF that triggers the spike-type stall inception. Finally, the stall control concept on the stage that first generates stall inception using self-recirculating injection is proposed. This study helps to guide the design of self-recirculating injection in actual application.
Uniaxial Ratchetting of Filled Rubber: Experiments and Damage-Coupled Hyper-Viscoelastic-Plastic Constitutive Model
Authors: Chen Yifu , Kang Guozheng , Yuan Jianghong , Yu Chao
Published: July 2018

A series of stress-controlled uniaxial cyclic tension-unloading tests are discussed to investigate the ratchetting of a filled rubber at room temperature. It is shown that obvious ratchetting occurs and depends apparently on the applied stress level, stress rate, and stress history. Based on the experimental observations, a damage-coupled hyper-viscoelastic-plastic constitutive model is then developed to describe the ratchetting of the filled rubber, which consists of three branches in parallel, i.e., a hyperelastic, a viscoelastic, and a plastic one. The damage is assumed to act equally on three branches and consists of two parts, i.e., the Mullins-type damage caused by the initial tensile deformation and the accumulated damage occurred during the cyclic deformation. The developed model is validated by comparing the predicted results with the experimental data.
A Computational Model of Bio-Inspired Soft Network Materials for Analyzing Their Anisotropic Mechanical Properties
Authors: Zhang Enrui , Liu Yuan , Zhang Yihui
Published: July 2018

Soft network materials constructed with horseshoe microstructures represent a class of bio-inspired synthetic materials that can be tailored precisely to match the nonlinear, J-shaped, stress–strain curves of human skins. Under a large level of stretching, the nonlinear deformations associated with the drastic changes of microstructure geometries can lead to an evident mechanical anisotropy, even for honeycomb and triangular lattices with a sixfold rotational symmetry. Such anisotropic mechanical responses are essential for certain targeted applications of these synthetic materials. By introducing appropriate periodic boundary conditions that apply to large deformations, this work presents an efficient computational model of soft network materials based on the analyses of representative unit cells. This model is validated through comparison of predicted deformed configurations with full-scale finite element analyses (FEA) for different loading angles and loading strains. Based on this model, the anisotropic mechanical responses, including the nonlinear stress–strain curves and Poisson's ratios, are systematically analyzed for three representative lattice topologies (square, triangular and honeycomb). An analytic solution of the geometry-based critical strain was found to show a good correspondence to the critical transition point of the calculated J-shaped stress–strain curve for different network geometries and loading angles. Furthermore, the nonlinear Poisson's ratio, which can be either negative or positive, was shown to depend highly on both the loading angle and the loading strain.
Vortex Shedding and Frequency Lock in on Stand Still Wind Turbines—A Baseline Experiment
Authors: Lennie Matthew , Selahi-Moghaddam Alireza , Holst David , Pechlivanoglou George , Navid Nayeri Christian , Paschereit Christian Oliver
Published: July 2018

During the commissioning and stand-still cycles of wind turbines, the rotor is often stopped or even locked leaving the rotor blades at a standstill. When the blades are at a standstill, angles of attack on the blades can be very high, and it is therefore possible that they experience vortex-induced vibrations. This experiment and analysis helps to explain the different regimes of flow at very high angles of attack, particularly on moderately twisted and tapered blades. A single blade was tested at two different flow velocities at a range of angles of attack with flow tuft visualization and hotwire measurements of the wake. Hotwire wake measurements were able to show the gradual inception and ending of certain flow regimes. The power spectral densities of these measurements were normalized in terms of Strouhal number based on the projected chord to show that certain wake features have a relatively constant Strouhal number. The shedding frequency appears then to be relatively independent of chord taper and twist. Vortex generators (VGs) were tested but were found to have little influence in this case. Gurney flaps were found to modify the wake geometry, stall onset angles, and in some cases the shedding frequency.
Membrane-Enhanced Lamina Emergent Torsional Joints for Surrogate Folds
Authors: Chen Guimin , Magleby Spencer P. , Howell Larry L.
Published: July 2018

Lamina emergent compliant mechanisms (including origami-adapted compliant mechanisms) are mechanical devices that can be fabricated from a planar material (a lamina) and have motion that emerges out of the fabrication plane. Lamina emergent compliant mechanisms often exhibit undesirable parasitic motions due to the planar fabrication constraint. This work introduces a type of lamina emergent torsion (LET) joint that reduces parasitic motions of lamina emergent mechanisms, and presents equations for modeling parasitic motion of LET joints. The membrane joint also makes possible one-way joints that can ensure origami-based mechanisms emerge from their flat state (a change point) into the desired configuration. Membrane-enhanced LET (M-LET) joints, including one-way surrogate folds, are described here and show promise for use in a wide range of compliant mechanisms and origami-based compliant mechanisms. They are demonstrated as individual joints and in mechanisms such as a kaleidocycle (a 6R Bricard linkage), degree-4 origami vertices (spherical mechanisms), and waterbomb base mechanisms (an 8R multi-degrees-of-freedom origami-based mechanism).
Dough Extrusion Forming of Titanium Alloys—Green Body Characteristics, Microstructure and Mechanical Properties
Authors: Srivas Pavan Kumar , Kapat Kausik , Wan Meher , Dhara Santanu
Published: July 2018

Titanium and its alloys are widely used in structural applications owing to superior mechanical properties and corrosion resistance. In the present study, a simple powder metallurgy-based process is developed to fabricate dense components through formation of dough under ambient condition using Ti6Al4V powder along with chitosan powder as dough forming additive and acetic acid as solvent. The prepared samples had ∼66±1.7% green density and 97.3±2.1% sintered density of the theoretical value. The microstructure of Ti6Al4V was investigated using scanning electron microscopy (SEM) combined with energy-dispersive X-ray (EDX) spectroscopy. Micro-CT analysis was carried out for distribution of defects and their influence on flexural strength and microhardness was assessed as well. The prepared green samples had uniform particle distribution that resulted in minimum deformation after sintering. Assessment of mechanical properties revealed that the values of hardness and flexural modulus for sintered samples were comparable to the reported values of Ti6Al4V components prepared using other process. Therefore, the developed method of dough forming for dense titanium components using powder metallurgy route is a simple and viable alternative.
The Impact of Predried Lignite Cofiring With Hard Coal in an Industrial Scale Pulverized Coal Fired Boiler
Authors: Pawlak-Kruczek Halina , Lewtak Robert , Plutecki Zbigniew , Baranowski Marcin , Ostrycharczyk Michal , Krochmalny Krystian , Czerep Michal , Zgora Jacek , Niedzwiecki Lukasz
Published: July 2018

The paper presents the experimental and numerical study on the behavior and performance of an industrial scale boiler during combustion of pulverized bituminous coal with various shares of predried lignite. The experimental measurements were carried out on a boiler WP120 located in CHP, Opole, Poland. Tests on the boiler were performed during low load operation and the lignite share reached over to 36% by mass. The predried lignite, kept in dedicated separate bunkers, was mixed with bituminous coal just before the coal mills. Computational fluid dynamic (CFD) simulation of a cofiring scenario of lignite with hard coal was also performed. Site measurements have proven that cofiring of a predried lignite is not detrimental to the boiler in terms of its overall efficiency, when compared with a corresponding reference case, with 100% of hard coal. Experiments demonstrated an improvement in the grindability that can be achieved during co-milling of lignite and hard coal in the same mill, for both wet and dry lignite. Moreover, performed tests delivered empirical evidence of the potential of lignite to decrease NOx emissions during cofiring, for both wet and dry lignite. Results of efficiency calculations and temperature measurements in the combustion chamber confirmed the need to predry lignite before cofiring. Performed measurements of temperature distribution in the combustion chamber confirmed trend that could be seen in the results of CFD. CFD simulations were performed for predried lignite and demonstrated flow patterns in the combustion chamber of the boiler, which could prove useful in case of any further improvements in the firing system. CFD simulations reached satisfactory agreement with the site measurements in terms of the prediction of emissions.