Engineering Design Considerations Research Articles

A multi-length-scale investigation of the applicability of ductility laws for annealed and work-hardened copper

Small-scale mechanical testing provides unique advantages over conventional testing in investigating the mechanical response of nuclear materials. While small-scale testing enables accelerated materials research, it raises the question of comparability to large-scale properties for engineering design considerations. Among different mechanical properties for structural design considerations such as yield and ultimate tensile stress, ductility is of critical importance with respect to structural component health. The effectiveness of using small-scale mechanical testing for probing these mechanical properties is dictated by understanding how the mechanical responses translate from the microscale to the engineering scale. Therefore, a better understanding of size scaling effects via gathering and analysis of experimental data is required to bridge length-scales. This work builds upon previous reports to provide statistical data on how mechanical response changes as the size of the specimens are reduced from conventional sizes. One hundred twenty mesoscale tensile coupons of oxygen-free high thermal conductivity (OFHC) copper in work-hardened and annealed state have been manufactured using micro-wire electrical discharge machining (EDM) and tested under uniaxial tension. The mesoscale specimens have dimensions dictated by pre-selected geometric ratios (i.e., gauge section length over the square root of the cross-section area) with gauge length dimensions of 3 mm (or less) and sub-millimeter gauge widths and thicknesses. The mesoscale responses were compared to bulkscale properties to reveal the effect of specimen size on the mechanical response as a function of grain size and material state for a single phase face-centered cubic metal.

Aeroponic systems design: considerations and challenges

Controlled Environment Agriculture (CEA) holds promise as a way to intensify current agricultural production systems while limiting pressures on land, water, and energy resources. However, its use has not yet been widely adopted, in part because the engineering design considerations and associated challenges are not well known. This is even more apparent for aeroponics, where the additional cost and complexities in controlling atomization have yet to establish an advantage in scale over simpler hydroponic systems To shed light on these considerations and challenges, an instrumented aeroponic system was prototyped with the goal of creating a quantitative model of growth for various species of leafy greens. As the first consideration, pressure swirl atomizers were paired with a diaphragm-type pressure tank to supply the necessary pressures needed for effective atomization. Secondly, nutrient solution was mixed on-demand from Reverse Osmosis (RO) water and concentrated nutrient stock then pumped into the pressure tank using a positive displacement pump. A bamboo-based substrate that allowed both germination and extended vegetative growth was supported on a stainless steel mesh and PVC frame acting as a grow tray. Finally, a camera microservice platform was developed to quantify plant growth using a computer vision pixel-based segmentation method.

Electromagnetic and Engineering Design of a High-Current 15-MeV/u Cyclotron

The capability to produce high current, low loss, and extracted external ion beams presents an enabling technology for nuclear security, isotope production, and medical applications. We report on a novel, continuous-wave cyclotron for accelerating light ions with a charge-to-mass ratio of 1/2, which is designed for 1 mA maximum and 15 MeV/u energy. This article details the conceptual electromagnetic (EM) and engineering design including the 1.1 T sector magnets and 45 MHz, 200 kV radio frequency (RF) cavities. We discuss the cyclotron beam parameters with respect to potential commercial and industrial applications. The general concept and the accelerator's layout are followed by a detailed EM design of magnets and RF cavities. Finally, practical engineering design considerations will be provided.

Perspective of sol-gel hydrophobic silica deposited using low-pressure cold spray and ultrasonic atomizing for automotive coatings

The automotive sector is under constant pressure to minimize fuel consumption and reduce pollution emissions while maintaining a declining tendency for weight and cost reduction. This makes the material selection process a major of engineering design considerations. In the paper, the main automotive requirements were formulated to analyze the potential of selected deposition (low pressure cold spray and ultrasonic atomizing) and material fabrication (sol-gel method) techniques for application in the automotive industry.

RF deflecting cavity for fast radioactive ion beams

The Facility for Rare Isotope Beams (FRIB) will be a new scientific user facility that produces rare-isotope beams for experiments from the fragmentation of heavy ions at energies of 100–200 MeV/u. During the projectile fragmentation, the rare isotope of interest is produced along with many contaminants that need to be removed before the beam reaches detectors. At FRIB, this is accomplished with a magnetic projectile fragment separator. However, to achieve higher beam purity, in particular for proton-rich rare isotopes, additional purification is necessary. RadiaBeam in collaboration with Michigan State University (MSU) has designed a 20.125 MHz radiofrequency (RF) fragment separator capable of producing a 4 MV kick with 18 cm aperture in order to remove contaminant isotopes based on their time of flight. In this paper, we will discuss the RF and engineering design considerations of this separator cavity.

Design of G-band 500 W sheet beam extended-interaction klystron

High power generation in terahertz frequency band is limited by physical mechanism. A G-band sheet beam extended-interaction klystron was designed to demonstrate the power level and the physical factors that affect the performance of the klystron. An elliptical electron beam with a voltage of 24.5 kV, a current of 0.6 A and the dimension of 1 mm×0.15 mm was used. To match the size of the sheet beam and obtain high efficiency and high gain, the transverse-oversized barbell type multi-gap resonant cavity was used as the interaction circuit. The 3D PIC simulation results show that more than 500 W of power output can be obtained with the actual cavity loss considered, and the electron efficiency and gain are 3.65% and 38.2 dB respectively. It is found that the power and efficiency are largely restricted by the mode stability of the multi-gap cavity as well as the ohmic loss. The ohmic loss of the output cavity has a significant effect on the final output power which should be given special consideration in engineering design. The research in this paper has laid a good foundation for the development of high frequency sheet beam extended-interaction devices.

Advances in axial turbine blade profile aerodynamics

The aerodynamic performance of axial turbines depends significantly on profile losses, secondary flow losses, and clearance gap losses of vanes and blades. In modern high-efficiency turbomachinery operating at various working conditions, profile losses are very important criteria for the development of vanes and blades, and turbine designers strive to minimize the losses, based on better understandings of flow and loss characteristics at various working conditions. This paper summarizes recent advances in the field of turbine blade profile aerodynamics, and covers: (1) flow and loss characteristics of blade profiles, (2) flow structure and loss mechanism for transonic blade profiles, (3) off-design performance, (4) flow control, (5) design and optimization, (6) engineering design considerations, and (7) research methods of blade profile aerodynamics. The emphasis is placed on flow characteristics and loss control methods, and present insights regarding the current research trends and the prospects for future developments.

Enrich and Expand Rare Antigen-specific T Cells with Magnetic Nanoparticles.

We have developed a tool to both enrich and expand antigen-specific T cells. This can be helpful in cases such as to A) detect the existence of antigen-specific T cells, B) probe the dynamics of antigen-specific responses, C) understand how antigen-specific responses affect disease state such as autoimmunity, D) demystify heterogeneous responses for antigen-specific T cells, or E) utilize antigen-specific cells for therapy. The tool is based on a magnetic particle that we conjugate antigen-specific and T cell co-stimulatory signals, and that we term as artificial antigen presenting cells (aAPCs). Consequently, since the technology is simple to produce, it can easily be adopted by other laboratories; thus, our purpose here is to describe in detail the fabrication and subsequent use of the aAPCs. We explain how to attach antigen-specific and co-stimulatory signals to the aAPCs, how to utilize them to enrich for antigen-specific T cells, and how to expand antigen-specific T cells. Furthermore, we will highlight engineering design considerations based on experimental and biological information of our experience with characterizing antigen-specific T cells.

Four-harmonic buncher for radioactive and stable beams switching at the ATLAS facility

The Argonne Tandem Linac Accelerator System (ATLAS) is planning an upgrade to a multi-user facility to simultaneously accelerate both stable beams from an ECR ion source and radioactive beams from an Electron Beam Ion Source charge breeder. The ATLAS Multi-User Upgrade will need to provide high transmission of ion beams with a mass-to-charge ratio up to 7 as it enables more options to alternate radioactive and stable beams. Currently, the bunching is provided with a lumped circuit multi-harmonic buncher, which cannot effectively operate at the required amplitude of the saw-tooth voltage for ions with mass-to-charge ratio of 7 due to thermal issues.RadiaBeam Systems in collaboration with Argonne National Laboratory has designed a four-harmonic coaxial resonator buncher with the ATLAS fundamental frequency of 12.125 MHz, and a compact, less than 2-m-long, footprint, capable of providing the required voltage of 6.2 kV. This device allows fast and reliable pre-bunching of DC ion beams with the capability of fast switching of heavy-ion radioactive and stable beams for delivery to multiple users. In this paper, we will discuss the RF and engineering design considerations of this buncher.

Socially assistive robots: current status and future prospects for autism interventions

Socially assistive robots: current status and future prospects for autism interventions Laurie A Dickstein-Fischer,1 Darlene E Crone-Todd,2 Ian M Chapman,1 Ayesha T Fathima,3 Gregory S Fischer3 1Secondary and Higher Education Department, School of Education, Salem State University, Salem, MA, USA; 2Psychology Department, College of Arts and Sciences, Salem State University, Salem, MA, USA; 3Robotics Engineering Program, Worcester Polytechnic Institute, Worcester, MA, USA Abstract: Social robots interact with people through social interactions, physical assistance, and therapy delivery. Socially assistive robots (SARs) are specifically intended to assist in a therapeutic way to help build social behavior skills. One area where SARs have gained significant attention is in the treatment and diagnosis of autism spectrum disorder. With the increase in rates of individuals diagnosed with autism spectrum disorder, there is an increasing need for equitable and accessible applied behavior analysis (ABA) therapy services. Current barriers for sufficient access to therapy include high administrative burden, burnout rates on the part of ABA therapists, and affordability of services. One way to reduce administrative burden is to automate procedures using computer-based interventions, including SARs. SARs have the potential to increase client engagement, while at the same time making it possible for therapists to provide a more interactive session for their client. We argue that there is benefit to clients, therapists, scientists, and to the general public if behavior analysts can work with robotic design engineers for further research and development on SARs. Such collaboration is necessary for ensuring that robust SAR designs are embedded in conceptually systematic approaches to ABA, while at the same time integrating relevant engineering design considerations. This technological integration is important for the field of ABA to move forward as robotics become more commonplace, and to effectively address the cost, quality, and access considerations involved. Keywords: SARs, applied behavior analysis, autism therapy, therapeutic robots, human robot interaction, PABI, psychology, technology, computer aided instruction, ASD

Carbon nanotubes exhibit fibrillar pharmacology in primates.

Nanomedicine rests at the nexus of medicine, bioengineering, and biology with great potential for improving health through innovation and development of new drugs and devices. Carbon nanotubes are an example of a fibrillar nanomaterial poised to translate into medical practice. The leading candidate material in this class is ammonium-functionalized carbon nanotubes (fCNT) that exhibits unexpected pharmacological behavior in vivo with important biotechnology applications. Here, we provide a multi-organ evaluation of the distribution, uptake and processing of fCNT in nonhuman primates using quantitative whole body positron emission tomography (PET), compartmental modeling of pharmacokinetic data, serum biomarkers and ex vivo pathology investigation. Kidney and liver are the two major organ systems that accumulate and excrete [86Y]fCNT in nonhuman primates and accumulation is cell specific as described by compartmental modeling analyses of the quantitative PET data. A serial two-compartment model explains renal processing of tracer-labeled fCNT; hepatic data fits a parallel two-compartment model. These modeling data also reveal significant elimination of the injected activity (>99.8%) from the primate within 3 days (t1/2 = 11.9 hours). These favorable results in nonhuman primates provide important insight to the fate of fCNT in vivo and pave the way to further engineering design considerations for sophisticated nanomedicines to aid late stage development and clinical use in man.

Probabilistic risk assessment from potential exposures to the public applied for innovative nuclear installations

Potential exposures are those that may occur as a result of unanticipated operational performance or accidents. Potential exposure situations are probabilistic in nature because they depend on uncertain events such as equipment failure, operator errors or external initiators beyond the control of the operator. Consequently, there may exist a range of possible radiological impacts that need to be considered. In this paper a Level 3 Probabilistic Safety Assessment (PSA) for a hypothetical scenario relevant to Innovative Nuclear Energy Systems (INS) was conducted using computer code MACCS (MELCOR Accident Consequence Code Systems). The acceptability of an INS was analyzed taking into account the general requirement that relocation or evacuation measures must not be necessary beyond the site boundary. In addition, deterministic modeling of the accident consequences for the critical meteorological conditions was carried out using the JRODOS decision support system (Real-time On-line Decision Support system for off-site emergency management in Europe). The approach used for dose and risk assessment from potential exposure of accidental releases and their comparison with acceptance criteria are presented. The methodology described can be used as input to the licensing procedure and engineering design considerations to help satisfy relevant health and environmental impact criteria for fission or fusion nuclear installations.

Disinfecting and Stabilizing Biosolids Using E-Beam and Chemical Oxidants

Municipal sewage and sludges can harbor a variety of infectious microorganisms as well as estrogenic compounds and their metabolites. Biosolids and other residuals generated from municipal wastewater treatment facilities need to be used for beneficial purposes such as land application. To reduce the potential for adverse environmental and human impacts, it is critical that novel approaches be investigated so that municipal biosolids can be disinfected and stabilized to reduce the pathogen loads and levels of estrogenic compounds. The overall objective of this project was to demonstrate the disinfection and enhanced stabilization of municipal biosolids when high energy (10 MeV) Electron Beam (e-beam) technology is coupled with oxidants such as chlorine dioxide and ferrate.High energy E-Beam is effective as a disinfection technology. Significant reductions of all target organisms can be achieved in municipal biosolids depends on the dose that is employed. An e-beam treatment system utilizing 15 kGy e-beam dose has been designed and mathematically modeled and validated. Based on these engineering design considerations, e-beam treatment was shown to be cost-effective. There was synergistic disinfection of pathogens when e-beam is coupled with oxidants such as chlorine dioxide and ferrate. E-Beam at 8 kGy was unable to destroy estrogenic activity in the sludge samples. Ferrate (100 ppm) was capable of destroying estrogenic activity in the biosolid samples with or without the addition of e-beam irradiation. Chlorine dioxide (100 ppm) was not effective at destroying the estrogenic activity either by itself or in combination with e-beam. The combination of 100 ppm of ferrate with 8 kGy of e-beam promoted the stabilization of aerobic and anaerobic sludge samples as indicated by BOD, VSS and SOUR test results. The results demonstrate that 10 MeV e-beam is capable of cost-effectively inactivating a variety of bacterial and viral pathogens in aerobically and anaerobically digested biosolids. Overall, thes results suggest that when e-beam is combined with ferrate significant reductions of microbial pathogens, estrogenic compounds and biosolid stabilization can be achieved.This title belongs to WERF Research Report Series.ISBN: 9781843392996 (eBook)

Re-visiting 1-D hypervelocity penetration

Abstract Classical, one-dimensional theory of hydrodynamic penetration is used as the basis of establishing simplified analytical relationships describing energy, momentum, and power deposition during hypervelocity impact events. A concise overview of the 1-D model is given followed by a select grouping of terms into relationships that offer first-order criteria for making engineering design considerations on relevant applications and assist in the analysis of experimental observations. Momentum, energy, and power deposition are found to be proportional to second, third and fourth power exponents, respectively. These analytical terms are presented for constant velocity gradient, i.e. fixed length, rods as well as linear velocity gradient rods, such as shaped charge jets. The role of penetrator-to-target density ratio is then examined in terms of the backflow, or reverse flow of 1-D penetration. Again, the non-dimensional ratio of penetrator-to-target mass density is used to compare the relative velocity of material flow during penetration. The relationship highlights the role of penetrator materials for achieving desired effects in these hypervelocity, terminal ballistics events. Albeit the relationships are derived on the assumptions for hydrodynamic processes, their generality of form and ease of implementation make them a useful first-order description for engineering insight and application over a broad range of velocities.

The Angioguard™ embolic protection device

Endovascular management of cardiovascular disease is quickly becoming a more popular treatment. The effectiveness in using embolic protection devices (EPDs), such as the Angioguard™ XP filter, during carotid artery stenting (CAS) is a topic of ongoing controversy and scrutiny. Early clinical results indicate that EPDs can reduce complications associated with CAS. However, the incidence of stroke and postprocedural embolic events are statistically similar when comparing CAS with the gold standard in carotid stenosis repair, carotid endarterectomy (CEA). The focus of this manuscript is the critical evaluation of Angioguard XP with respect to numerous in vitro and ex vivo experiments, and clinical trials that have been conducted by the authors and other researchers to investigate the efficacy of EPDs with the objective of suggesting engineering design considerations for future generations of these devices. Angioguard XP has had mixed performance outcomes in in vitro testing reported in the literature. In our laboratory, this device had undesirable measures of performance in bench-top testing protocols using in vitro flow models. Technical considerations relevant to design of EPDs, such as ideal pore size, effective wall apposition in tortuous geometry and maximization of capture efficiency have not been addressed adequately in the literature. It is likely that in the future both CAS and CEA will coexist as potential forms of treatment in the clinical management of cerebrovascular disease.

Structural design innovation: Russia Tower

AbstractThe Russia Tower will be Europe's tallest building and one of the most distinctive high rises in the world. The striking 600 m (1968 ft) tall form and its structure evolved through a collaborative process between the architect, Foster + Partners of London, and structural engineer Halvorson & Partners of Chicago. The innovative ‘braced spine’ structural system developed in this process is an efficient concept for super‐tall structures and was a direct response to the design challenges and opportunities presented by this project. The design process between Foster and Halvorson that led to this unique tower design is described and several of its special structural engineering design considerations are discussed. Copyright © 2007 John Wiley & Sons, Ltd.

Geomorphic, Aquatic, and Engineering Design Considerations for Low-Water Crossings

A wide variety of low-water stream crossings have been built on low-volume roads across the United States over the past 50 years with the primary objectives of traffic access and cost savings. They are generally a rigid structure in a dynamic stream system, so most have worked to varying degrees from a road use standpoint. Many have required maintenance, repairs, or design modifications to function as they exist today. In addition, most structures have caused problems with regard to stream sediment transport, promoting upstream aggradation or downstream scour and creating barriers or limitations to the passage of aquatic organisms. Three fundamental types of fords both maintain good stream function and provide for traffic use: simple at-grade fords, low-water bridges, and vented fords with a large waterway opening area, preferably with a natural stream channel bottom. Each has a large waterway open area that does not constrict most flow. Ideally the width is at least equal to that of the natural bankfull channel. This paper discusses the problems observed and the requirements for a ford to meet stream function needs, pass sediment appropriately, provide for the passage of fish and other aquatic organisms, and meet engineering design needs. Some fords are designed specifically to function in extreme dynamic conditions, such as in debris torrent or alluvial fan channels, in desert or other “flashy” hydrologic regimes, or where debris jams and overbank flooding are frequent. Fitting the structure to the site requires experience and sound geomorphic, hydraulic, and engineering design. The task should be undertaken with an interdisciplinary team approach.

Investigation into cylinder-on-flat adhesion elastic–plastic micro-contact under repeated loading and unloading condition

The evolution of microcontact induced deformation and stress states under repeated loading and unloading condition is of great interest for the scientific understanding as well as from the engineering design considerations of microelectromechanical systems (MEMS) based switches and similar other devices since they operate under cyclic condition. This study, therefore, investigated the microcontact interaction between deformable smooth cylindrical segment and deformable smooth flat using the finite element analysis. Elastic and elastic–plastic material behaviors and adhesion interaction are considered. The detailed information about contact area, displacement and stress state in the contact region under cycling condition are presented. Contact area varies nonlinearly even when the applied load is varying linearly in a cycle. Additionally, contact areas during loading and unloading portions of a cycle are not equal at the same load level. The deformation and contact area increases in the presence of adhesion force and also with elastic–plastic material behavior. However, the adhesion force is reduced while the contact area is increased during the microcontact between elastic–plastic bodies in comparison to those between elastic bodies. The maximum increase in stress and deformation states occurs during the first cycle, and then slowly with increasing number of cycles. Further, the maximum stress state is not at the contact surface and also not at instant of the maximum applied external force. Finally, adhesion force during microcontact interaction can be of the same order as the applied external force. Therefore, design and analysis of microcontacts in micromechanical switches and similar other devices should include the effects of adhesion force and cyclic effects.

Investigation of a naphtha storage tank fire

AbstractIn October 1988, one of the world's largest combined loss storage tank fires occurred at a refinery located on the island of Pulau Merlimau, Singapore. At the height of the incident, the blaze involved three floating roof naphtha storage tanks, each approximately 134 feet in diameter and containing a total of 294,500 barrels of product. The resultant property loss was estimated at over USD 6.6 million in 1988 dollars.At several stages, the fire threatened to involve tankage in adjacent dikes containing kerosene, reformate, motor gasoline, and diesel product. Because the refinery was located on an island, equipment and manpower were ferried to the site. Despite the size of the fire and adverse logistics, fire‐fighting efforts were successful in containing the incident to the primary dike tankage.This paper investigates the incidents leading up to the fire, operational and design engineering considerations, and analyzes the basic fire‐fighting strategy, prefire and emergency response plans, fire water management, and fixed/semifixed foam systems. © 2005 American Institute of Chemical Engineers Process Saf Prog, 2005

Expression of heterologous proteins inPichia pastoris: a useful experimental tool in protein engineering and production

The use of the methylotrophic yeast, Pichia pastoris, as a cellular host for the expression of recombinant proteins has become increasing popular in recent times. P. pastoris is easier to genetically manipulate and culture than mammalian cells and can be grown to high cell densities. Equally important, P. pastoris is also a eukaryote, and thereby provides the potential for producing soluble, correctly folded recombinant proteins that have undergone all the post-translational modifications required for functionality. Additionally, linearized foreign DNA can be inserted in high efficiency via homologous recombination procedures to generate stable cell lines whilst expression vectors can be readily prepared that allow multiple copies of the target protein, multimeric proteins with different subunit structures, or alternatively the target protein and its cognate binding partners, to be expressed. A further benefit of the P. pastoris system is that strong promoters are available to drive the expression of a foreign gene(s) of interest, thus enabling production of large amounts of the target protein(s) with relative technical ease and at a lower cost than most other eukaryotic systems. The purpose of this review is to summarize important developments and features of this expression system and, in particular, to examine from an experimental perspective the genetic engineering, protein chemical and molecular design considerations that have to be taken into account for the successful expression of the target recombinant protein. Included in these considerations are the influences of P. pastoris strain selection; the choice of expression vectors and promoters; procedures for the transformation and integration of the vectors into the P. pastoris genome; the consequences of rare codon usage and truncated transcripts; and techniques employed to achieve multi-copy integration numbers. The impact of the alcohol oxidase (AOX) pathways in terms of the mut+ and mut(s) phenotypes, intracellular expression and folding pathways is examined. The roles of pre-pro signal sequences such as the alpha mating factor (alpha-MF) and the Glu-Ala repeats at the kex2p cleavage site on the processing of the protein translate(s) have also been considered. Protocols for the generation of protein variants and mutants for screening for orphan cognate binding partners and the use of experimental platforms addressing the molecular recognition behaviour of recombinant proteins such as the extracellular domains of transmembrane receptors with their physiological ligands are also described. Finally, the palindromic patterns of glycosylation that can occur with these expression systems, in terms of the role and location of the sequon in the primary structure, the number of mannose units and the types of oligosaccharides incorporated as Asn- or O-linkages and their impact on the thermostability and immunogenicity of the recombinant protein are considered. Procedures to prevent glycosylation through manipulation of cell culture conditions or via enzymatic and site-directed mutagenesis methods are also discussed.