bluuebunny/crossref_metadata_2025 huggingface dataset:
Identifying effective water‐management strategies in variable climates using population dynamics models
Authors: Yen Jian D. L. , Bond Nick R. , Shenton Will , Spring Daniel A. , Mac Nally Ralph
Published: March 2013

Water‐resource management should maintain ecological condition, including population viabilities of aquatic taxa. Many arid and semi‐arid regions have experienced elevated water regulation and face drying and warming climates.

 We combined stochastic, population dynamics models for four fish species with differing life histories with simulated regulated and unregulated flow regimes to assess the relative robustness of fish population persistence to different scenarios of climate change and water management.

 Water regulation had a larger effect than differences in climate, negatively affecting one species through increased summer flows, and stabilizing population trajectories for two species that were sensitive to cease‐to‐flow events; the other species was insensitive to regulation or climate.

 The greater importance of water regulation suggests that management of water regulation and human use can be used to insulate fish, to some degree, from the effects of future climate change.

 General deductions from our results, such as the importance of inter‐annual variability and the application of demographic modelling tools, are readily transferable to other systems.

 Synthesis and applications. Our scenario‐based approach was able to assess the population‐level effects of multiple concurrent stressors and represents an effective framework for identifying management strategies that are robust to uncertainty in future environments.
A practical, clinical approach to the assessment and management of suspected insulin allergy
Authors: Jacquier J. , Chik C. L. , Senior P. A.
Published: March 2013

Background

Although allergic reactions to insulin are uncommon, they can be difficult to diagnose and management may be very difficult in subjects with Type 1 diabetes with severe allergy. Access to allergists and specialist diagnostic tests is limited and few diabetes specialists are familiar with desensitization as a means of treating allergy. People with diabetes may develop symptoms which mimic insulin allergy but are attributable to other conditions.

Case reports

Here we describe three cases of insulin allergy. One patient presented with severe, albeit localized, urticarial reactions at injection sites. The most severe case was a woman with recent‐onset Type 1 diabetes who presented with grade 2 anaphylaxis. The third patient presented with generalized urticaria and angioedema. Insulin allergy was confirmed in all three cases.

Methods

Assessment involved measurement of immunoglobulin and anti‐insulin antibody levels. Skin testing was performed in two cases. Treatments included desensitization in one case, alternative insulin preparations, antihistamines and continuous subcutaneous insulin infusion. In all three cases of insulin allergy there has been successful resolution of symptoms.

Conclusions

The clinical assessment and investigation in cases of suspected insulin allergy is described, along with detailed algorithms for skin testing and desensitization. This case series demonstrates an approach to challenging cases of suspected insulin allergy which will be helpful for diabetes specialists.
A risk‐adjusted economic evaluation of alternative models of involvement of practice nurses in management of type 2 diabetes
Authors: Haji Ali Afzali H. , Gray J. , Beilby J. , Holton C. , Banham D. , Karnon J.
Published: March 2013

Aims

To determine the cost‐effectiveness of alternative models of practice nurse involvement in the management of type 2 diabetes within the primary care setting.

Methods

Linked routinely collected clinical data and resource use (general practitioner visits, hospital services and pharmaceuticals) were used to undertake a risk‐adjusted cost‐effectiveness analysis of alternative models of care for the management of diabetes patients. These models were based on the reported level of involvement of practice nurses in the provision of clinical‐based activities. Potential confounders were controlled for by using propensity score‐weighted regression analyses. The impact of alternative models of care on outcomes and costs was measured and incremental cost‐effectiveness estimated. The uncertainty around the estimates of cost‐effectiveness was illustrated through bootstrapping.

Results

Although the difference in total cost between two models of care was not statistically significant, the high‐level model was associated with better outcomes (larger mean reductions in HbA1c). The upper 95% confidence intervals showed that the incremental cost per 1% decrease in HbA1c is only $454, and per one additional patient to achieve an HbA1c value of less than 53 mmol/mol (7.0%) is $323. Further analyses showed little uncertainty surrounding the decision to adopt the high‐level model.

Conclusions

The results provide a strong indication that the high‐level model is a cost‐effective way of managing diabetes patients. Our findings highlight the need for effective incentives to encourage general practices to better integrate practice nurses in the provision of clinical services.
Essential tremor 10, 20, 30, 40: clinical snapshots of the disease by decade of duration
Authors: Louis E. D. , Gerbin M. , Galecki M.
Published: March 2013

Background and purpose

Essential tremor (ET) is a chronic, progressive neurological disorder in which disease burden may slowly accrue. There are few long‐term studies, and the clinical and functional status of patients, with each decade of disease duration, has not been documented in detail. We used cross‐sectional data on 335 patients with ET (disease duration 1–81 years) to produce clinical snapshots of the disease at each 10‐year milestone (i.e. < 10, 10–19, 20–29, 30–39, ≥ 40 years). We hope these data will be of value in clinical‐prognostic settings both to patients and their treating physicians.

Methods

In this cross‐sectional, clinical‐epidemiological study at Columbia‐University Medical Center, each patient underwent a single evaluation, including self‐reported measures of tremor‐related disability, performance‐based measures of function, and neurologist‐assessments of tremor type, location and severity.

Results

A variety of metrics of tremor severity increased across the 10‐year time intervals. By ≥ 40 years duration, one‐third of patients had tremor in at least two cranial locations (neck, voice, jaw), and the proportion with high‐amplitude tremor reached 20.3% (while drawing spirals), 33.8% (spilling while drinking) and 60.8% (spilling while using a spoon). Yet even in the longest tremor duration group, very few (< 10%) were incapacitated (i.e. completely unable to perform the above‐mentioned tasks), and one‐third continued to exhibit no cranial tremor.

Conclusions

These data paint a picture of progressive decade‐by‐decade decline in ET. Yet patients with long disease duration did not relentlessly converge at the same end‐stage of severe, functionally incapacitating, diffuse tremor. In this respect, long‐duration ET patients presented a heterogeneous picture.
Telomere length and ischaemic stroke in women: a nested case–control study
Authors: Schürks M. , Prescott J. , Dushkes R. , De Vivo I. , Rexrode K. M.
Published: March 2013

Background and purpose

Telomere shortening has been implicated in cardiovascular disease (CVD). However, prospective data on the association between relative telomere length (RTL) and ischaemic stroke are scarce and inconclusive.

Methods

We used a nested case–control design among women participating in the prospective Nurses' Health Study. Participants provided blood samples in 1990 and were followed till 2006. Women with confirmed incident ischaemic stroke were matched to controls by age, smoking, postmenopausal status and postmenopausal hormone use. Quantitative polymerase chain reaction was used to determine RTL in genomic DNA extracted from peripheral blood leukocytes. Conditional logistic regression was used to determine the risk of ischaemic stroke associated with RTL, using RTL quartiles and as dichotomous according to the median.

Results

Data on RTL were available from 504 case–control pairs. Results did not suggest an association between RTL and ischaemic stroke. The odds ratio (OR) for ischaemic stroke was 0.82 [95% confidence interval (CI) 0.52–1.32] comparing lowest with the highest RTL quartile and 0.90 (95% CI 0.65–1.24) comparing RTL below the median with RTL above the median. Associations were unchanged after additional adjustment for cardiovascular risk factors. Further analyses suggested an association between RTL and fatal ischaemic stroke (54 case–control pairs; lowest versus highest quartile OR = 1.99, 95%CI 0.26–14.9); however, results were statistically insignificant.

Conclusion

In this large nested case–control study among women RTL was not associated with ischaemic stroke. In light of the varying study results in the literature on the association between telomere length and stroke, additional research is warranted.
Changes in Affective Profiles of Postsecondary Students in Lower‐Level Foreign Language Classes
Authors: Kondo‐Brown Kimi
Published: March 2013

Recent surveys and research on second language (L2)/foreign language acquisition help explain the challenges that postsecondary students in lower‐level foreign language (FL) courses may experience. The present study extends this line of research by examining changes in students' affective profiles in a two‐year Japanese program (n = 382) at an American university. The results indicated that students who reached the end of the program perceived more social, economical, integrative, and other value in learning Japanese than those at the beginning of the program. Results also showed that students appeared to expend significantly less effort in learning the language at the end of the program than at the beginning. This article urges FL instructors, especially those in lower‐level courses, to carefully consider issues of motivation in these and other courses.
Autobiographical memory in Parkinson's disease: A retrieval deficit
Authors: Souchay Celine , Smith Sarah Jane
Published: March 2013

This study examined the effects of providing cues to facilitate autobiographical memory retrieval in Parkinson's disease. Previous findings have shown that individuals with Parkinson's disease retrieve fewer specific autobiographical memories than older adult controls. These findings are clinically significant since the quality of autobiographical memory is linked to identity and sense of self. In the current study, 16 older adults with Parkinson's disease without dementia and 16 matched older adult controls were given 3 min in which to recall autobiographical memories associated with five different time periods and to give each memory a short title. Participants were later asked to retrieve the memories in three phases: firstly in a free recall phase; secondly in response to general cues (time periods) and finally in response to specific cues (the short titles previously given). The number of memories and the quality of the memory (general or specific) was recorded in each condition. Compared with matched older adult controls, the Parkinson's disease group was impaired in retrieving the memories that they had previously given in the free recall phase and in response to general cues. The performance of the group with Parkinson's disease was only equivalent to the older adults when they retrieved memories in response to self‐generated cues. The findings are discussed in relation to theories of autobiographical memory and the neuropsychology of Parkinson's disease.
Refractory metal nuggets within presolar graphite: First condensates from a circumstellar environment
Authors: Croat T. K. , Berg T. , Bernatowicz T. , Groopman E. , Jadhav M.
Published: March 2013

Transmission electron microscope (TEM) investigations have revealed Os, Ru, Mo‐rich refractory metal nuggets within four different presolar graphites, from both the high‐density (HD) Murchison (MUR) and low‐density (LD) Orgueil (ORG) fractions. Microstructural and chemical data suggest that these are direct condensates from the gas, rather than forming later by exsolution. The presolar refractory metal nugget (pRMN) compositions are variable (e.g., from 8 < Os atom% < 77), but follow the same chemical fractionation trends as isolated refractory metal nuggets (mRMNs) previously found in meteorites (Berg et al. 2009). From these compositions one can infer a temperature of last equilibration with the gas of 1405–1810 K (e.g., Berg et al. 2009 at approximately 100 dyne cm−2 pressure), which implies that the host graphites form over roughly the same range (in agreement with predictions) and that the pRMNs are chemically isolated from the gas when captured by graphite. Further, the pRMN compositions give evidence that HD graphites form at a higher T than LD ones. Chemical and phase similarities with the isolated mRMNs suggest that the mRMNs also condense directly from a gas, although from the early solar nebula rather than a presolar environment. Although the pRMNs themselves are too small for detection of isotopic anomalies, NanoSIMS isotopic measurements of their host graphites confirm a presolar origin for the assemblages. The two pRMN‐containing LD graphites show evidence of a supernova (SN) origin, whereas the stellar origins of the pRMNs in HD graphite are unclear, because only less‐diagnostic 12C enrichments are detectable (as is commonly true for HD graphites).
Direct Left Ventricular Endocardial Pacing: An Alternative When Traditional Resynchronization Via Coronary Sinus Is Not Feasible or Effective
Authors: MORIÑA‐VÁZQUEZ PABLO , ROA‐GARRIDO JESSICA , FERNÁNDEZ‐GÓMEZ JUAN M. , VENEGAS‐GAMERO JOSÉ , PICHARDO RAFAEL B. , CARRANZA MANUEL H.
Published: March 2013

Background

Biventricular pacing through the coronary sinus (CS) is effective for the treatment of patients with heart failure and left bundle‐branch block. However, this approach is not always feasible. Although surgical epicardial lead implantation is an alternative, the technique may be deleterious in some patients. Thus, direct left ventricular (LV) endocardial pacing under local anesthesia may be an option.

Objective

We describe our technique and analyze the results of direct LV endocardial pacing.

Method

Fourteen patients with failed resynchronization via CS (April 2006–September 2011) were selected. Using a femoral approach, we performed transseptal puncture and LV mapping, then fixed the active lead where the longest electrical delay was observed; the generator was placed in the anterior thigh. For resynchronization, eight patients with a device previously implanted through the upper veins received a single‐chamber generator that was set to the VVT mode to sense the subclavian pacing spike. Six patients received a complete femoral resynchronization system with either a defibrillator or pacemaker. Patients were followed for 6–54 months.

Results

The LV lead was successfully implanted in all cases. Two patients experienced excessive bleeding and two died during follow‐up. All except one improved at least one New York Heart Association class and experienced improved left ventricle ejection fraction. One patient with recurrent episodes of ventricular fibrillation was asymptomatic.

Conclusion

Direct LV endocardial pacing is safe and may be a less risky, more efficient alternative than surgical epicardial lead implantation for resynchronization via CS.
The Beneficial Influence of Bauschinger Effect Mitigation on the Barrel's Safe Maximum Pressure
Authors: Perl M. , Perry J.
Published: March 2013

The favorable residual stress field generated by the autofrettage process is increasing the barrel's capacity to withstand pressure during firing—defined as the reloading phase. There are two principal autofrettage processes: swage autofrettage and hydraulic autofrettage. While the theoretical solution for hydraulic autofrettage has been available and accessible for a long time, the available models for swage autofrettage have been quite limited. Both processes include two successive stages of pressure loading and unloading followed by an additional reloading during firing. Reyielding during the firing phase of an autofrettaged barrel is strongly affected by the secondary Bauschinger effect (BE) that involves a reduction of the yield stress in tension due to previous plastic deformation in compression, occurring in the unloading phase of the autofrettage process. The secondary Bauschinger effect can be completely mitigated by introducing a low temperature heat treatment (LTHT) immediately after the autofrettage process, thus increasing the barrel's safe maximum pressure (SMP). The aim of the present work is to quantitatively analyze the effect of low temperature heat treatment on the safe maximum pressure of a gun barrel. Two extreme cases are considered: In the first case, it is assumed that low temperature heat treatment was applied to the barrel, and that it completely mitigated the secondary Bauschinger effect, while in the second case it is assumed that no low temperature heat treatment was applied to the barrel. Both the swage and the hydraulic autofrettage processes are numerically analyzed using a newly developed 3D computer code. The numerical results confirm that a low temperature heat treatment, which fully eliminates the influence of the secondary Bauschinger effect, increases the barrel's safe maximum pressure especially in the case of hydraulic autofrettage.
Design Optimization of Compound Cylinders Subjected to Autofrettage and Shrink-Fitting Processes
Authors: Abdelsalam Ossama R. , Sedaghati Ramin
Published: March 2013

The autofrettage and shrink-fit processes are used to increase the load bearing capacity and fatigue life of the pressure vessels under thermomechanical loads. In this paper, a design optimization methodology has been proposed to identify optimal configurations of a two-layer cylinder subjected to different combinations of shrink-fit and autofrettage processes. The objective is to find the optimal thickness of each layer, autofrettage pressure and radial interference for each shrink-fit, and autofrettage combination in order to increase the fatigue life of the compound cylinder by maximizing the beneficial and minimizing the detrimental residual stresses induced by these processes. A finite element model has been developed in ansys environment to accurately evaluate the tangential stress profile through the thickness of the cylinder. The finite element model is then utilized in combination with design of experiment (DOE) and the response surface method (RSM) to develop a smooth response function which can be effectively used in the design optimization formulation. Finally, genetic algorithm (GA) combined with sequential quadratic programming (SQP) has been used to find global optimum configuration for each combination of autofrettage and shrink-fit processes. The residual stress distributions and the mechanical fatigue life based on the ASME code for high pressure vessels have been calculated for the optimal configurations and then compared. It is found that the combination of shrink-fitting of two base layers then performing double autofrettage (exterior autofrettage prior to interior autofrettage) on the whole assembly can provide higher fatigue life time for both inner and outer layers of the cylinder.
Finite-Temperature Quasi-Continuum
Authors: Tadmor E. B. , Legoll F. , Kim W. K. , Dupuy L. M. , Miller R. E.
Published: March 2013

A generalization of the quasi-continuum (QC) method to finite temperature is presented. The resulting "hot-QC" formulation is a partitioned domain multiscale method in which atomistic regions modeled via molecular dynamics coexist with surrounding continuum regions. Hot-QC can be used to study equilibrium properties of systems under constant or quasistatic loading conditions. Two variants of the method are presented which differ in how continuum regions are evolved. In "hot-QC-static" the free energy of the continuum is minimized at each step as the atomistic region evolves dynamically. In "hot-QC-dynamic" both the atomistic and continuum regions evolve dynamically in tandem. The latter approach is computationally more efficient, but introduces an anomalous “mesh entropy" which must be corrected. Following a brief review of related finite-temperature methods, this review article provides the theoretical background for hot-QC (including new results), discusses the implementational details, and demonstrates the utility of the method via example test cases including nanoindentation at finite temperature.
Effects of Tube Row on Heat Transfer and Surface Wetting of Microscale Porous-Layer Coated, Horizontal-Tube, Falling-Film Evaporator
Authors: Köroğlu Batikan , Bogan Nicholas , Park Chanwoo
Published: March 2013

An experimental study was conducted to investigate the effects of tube row on surface wetting and heat transfer of a horizontal-tube, falling-film evaporator. Two types of the evaporator tubes were used for comparison: plain copper and copper coated with a microscale porous-layer. Distilled water was used as solution and heating fluids. A visual observation experiment performed in ambient with no heat input showed that when solution fluid was dripped onto the evaporator tubes from a solution dispenser, the plain tubes were partially wetted, while the porous-layer coated tubes were completely wetted due to capillary liquid spreading, even at low solution flow rates. It was found from the heat transfer experiment performed in a closed chamber under saturated conditions that the porous-layer coated tubes exhibited superior evaporation heat transfer (up to 100% overall improvement over the plain tubes at low solution flow rates) due to complete solution wetting and thin-film evaporation. It was also observed that the surface wetting and heat transfer are greatly influenced by both intertube flow mode of solution fluid and tube wall superheat. The effects of the tube row on the solution wetting and heat transfer were significant, especially for downstream tubes.
An Al/Zr-Based Clay Stabilizer for High pH Applications
Authors: El-Monier Ilham A. , Nasr-El-Din Hisham A.
Published: March 2013

Sandstone formations are exposed to a variety of high pH fluids, including: hydraulic fracturing using high pH borate gels, alkaline-based chemical enhanced oil recovery (EOR) methods, water-based drilling fluids, and cementing filtrate. High pH values can trigger fines migration, and subsequent loss of permeability and well productivity. An aluminum/zirconium-based (Al/Zr) clay stabilizer was developed to control fines migration at high pH applications. The objective of this study is to assess the effectiveness of this new stabilizer and compare its performance with commercially available stabilizers. Laboratory studies were performed using Berea sandstone (8 wt. % clays; mainly kaolinite) cores, 6 in. length and 1.5 in. diameter. Tetramethyl ammonium chloride (TMAC) and choline chloride were used for comparison as two commercial clay stabilizers. Various coreflood experiments were conducted to determine the effect of the three stabilizers on core permeability (from 64 to 100 mD) at various temperatures up to 300 °F. In these experiments, a preflush that included 2 wt. % stabilizer was injected, followed by injection of 2 wt. % NaOH solution. The latter represented high pH filtrate that can invade the formation during any treatment that includes alkaline fluids. The pressure drop across the core was measured and samples of the core effluent were collected. Inductively coupled plasma optical emission spectrometry (winlab32 software) was used to measure the concentrations of Al, Zr, Fe, Ca, and Mg. ZetaPALS (BIC software) was used to measure the surface charge on the kaolinite particles. Lab results indicated that the new clay stabilizer worked effectively up to 300 °F following 2 wt. % NaOH. No reduction in permeability was noted in any of coreflood tests using sandstone cores of various initial permeabilities. The concentrations of various cations were found to be a function of core mineralogy. TMAC and choline chloride were not effective when followed by fresh water and incompatible with the high pH fluids. The new stabilizer is environmentally friendly, and can be used in hydraulic fracturing, and alkaline-based chemical EOR methods to mitigate clay related problems.
Efficiency Improvement in Precombustion CO2 Removal Units With a Waste–Heat Recovery ORC Power Plant
Authors: Trapp Carsten , Colonna Piero
Published: March 2013

This paper presents an analysis about recovering low-grade thermal energy from a precombustion CO2 capture process as part of an integrated gasification combined cycle (IGCC) power plant by means of organic rankine cycle (ORC) turbogenerators. The distinguishing feature of this system is the thermal energy source that is a syngas-water mixture, which is cooled from a temperature of approximately 140 °C, and partly condenses due to the heat transfer to the ORC primary heat exchanger. This study explores various types of ORC power systems for this application. The performance of commercially available ORC units is used as a benchmark and compared to the performance of two types of tailor-designed ORC power plants. The working fluid has a major influence on system performance and other technical and economic factors. The effect of selecting a fluid from the hydrocarbon and refrigerant families are therefore investigated, targeting the maximum net power output. In addition to pure fluids, two-component mixtures are also considered. The use of mixtures as working fluids in subcritical heat-recovery ORC systems allows for a better match of the temperature profiles in the primary heat exchanger and the condenser due to the temperature glide associated with phase-transition, leading to lower irreversibilities within the heat exchanging equipment. In order to further improve the thermal coupling between the cooling heat source and the heating of the working fluid, the supercritical cycle configuration is also studied. The performance of the three categories of systems, depending on working fluid and cycle configuration, i.e., systems based on (i) commercially available units, (ii) tailor-designed subcritical cycle, (iii) tailor-designed supercritical cycle, are analyzed in terms of net power output, second law efficiency, and component-based exergy efficiencies. The analysis shows that an improvement of 38.0% in terms of net power output compared to the benchmark system can be achieved by an optimized supercritical ORC power plant using an R134a/R236fa mixture as the working fluid. It is estimated that the total power consumption of the considered exemplary CO2 capture plant can be reduced by approximately 10% with the optimal ORC system. In this study, particular attention is focused on the semi-empirical optimization approach, in order to avoid unnecessary computations, and general guidelines are provided.
Assessment of Waste Heat Recovery From a Heavy-Duty Truck Engine by Means of an ORC Turbogenerator
Authors: Lang Wolfgang , Colonna Piero , Almbauer Raimund
Published: March 2013

This paper documents a feasibility study on a waste heat recovery system for heavy-duty truck engines based on an organic Rankine cycle (ORC) turbogenerator. The study addresses many of the challenges of a mobile automotive application: The system must be simple, efficient, relatively small, lightweight, and the working fluid must satisfy the many technical, environmental, and toxicological requirements typical of the automotive sector. The choice of a siloxane as the working fluid allows for the preliminary design of an efficient radial turbine, whose shaft can be lubricated by the working fluid itself. The system's heat exchangers, though more voluminous than desirable, are within acceptable limits. The simulated ORC system would add approximately 9.6 kW at the design point, corresponding to a truck engine power output of 150 kW at 1500 rpm. Future work will be devoted to further system and components optimization by means of simulations, to the study of dynamic operation and control, and will be followed by the design and construction of a laboratory test bench for mini-ORC systems and components.
Ensemble Noise-Reconstructed Empirical Mode Decomposition for Mechanical Fault Detection
Authors: Yuan Jing , He Zhengjia , Ni Jun , Brzezinski Adam John , Zi Yanyang
Published: March 2013

Various faults inevitably occur in mechanical systems and may result in unexpected failures. Hence, fault detection is critical to reduce unscheduled downtime and costly breakdowns. Empirical mode decomposition (EMD) is an adaptive time-frequency domain signal processing method, potentially suitable for nonstationary and/or nonlinear processes. However, the EMD method suffers from several problems such as mode mixing, defined as intrinsic mode functions (IMFs) with incorrect scales. In this paper, an ensemble noise-reconstructed EMD method is proposed to ameliorate the mode mixing problem and denoise IMFs for enhancing fault signatures. The proposed method defines the IMF components as an ensemble mean of EMD trials, where each trial is obtained by sifting signals that have been reconstructed using the estimated noise present in the measured signal. Unlike traditional denoising methods, the noise inherent in the input data is reconstructed and used to reduce the background noise. Furthermore, the reconstructed noise helps to project different scales of the signal onto their corresponding IMFs, instrumental in alleviating the mode mixing problem. Two critical issues concerned in the method, i.e., the noise estimation strategy and the number of EMD trials required for denoising are discussed. Furthermore, a comprehensive noise-assisted EMD method is proposed, which includes the proposed method and ensemble EMD (EEMD). Numerical simulations and experimental case studies on accelerometer data collected from an industrial shaving process are used to demonstrate and validate the proposed method. Results show that the proposed method can both detect impending faults and isolate multiple faults. Hence, the proposed method can act as a promising tool for mechanical fault detection.
A Knowledge-Driven, Network-Based Computational Framework for Product Development Systems
Authors: Yassine Ali A. , Bradley Joe A.
Published: March 2013

Today's fast-paced product development (PD) environment brings many new challenges to the PD community. These challenges are mainly due to a drastic increase in the scale and complexity of engineered systems, which require the collaboration of functionally and geographically distributed resources within and outside a firm's boundary. To address these new challenges, this paper proposes a novel theoretical and computational framework for an enterprise-wide PD management system. The proposed framework considers an integrative view of the various dependencies that co-exist in three PD domains (i.e., people, products, and processes). Additionally, it provides a computational tool that links them together in a succinct and tractable way and provides an analysis method for assessing their influence on shaping the product development process. Using this framework, we suggest that the characteristics of how an organization acquire data, interpret information, and apply knowledge will impact the final architecture of a product. We demonstrate this framework by analyzing the development efforts for a software project called robocode.
Fracture Height Containment in the Stimulation of Oriskany Formation
Authors: Vatsa Tushar , Yilin Wang John
Published: March 2013

The Oriskany sandstone formation has been a prolific producer of natural gas in the Appalachian basin since 1930s. Lot of production wells have been converted to gas storage wells for the ease of operation. Natural gas storage industry is a vital part of North American energy driven economy because of the fluctuation in seasonal demand and in maintaining the reliability of supply needed to meet the demands of the consumer. However, the storage wells suffer from an annual deliverability loss of 5% owing to the various damage mechanisms. A lot of work pertaining to the issue of identification of damage mechanisms and subsequent development of stimulation technology in order to mitigate the damage and restore the wells deliverability have been done in a joint effort between The Gas Research Institute, Department of Energy, American Gas Association and the various other operator companies involved in the storage industry. Operators mostly rely on traditional methods such as blowing, washing, reperforating, acidizing, infill drilling to restore wells deliverability. These traditional methods do provide short term benefits, but the longevity is not sustained and the overall situation remains same. Hydraulic fracturing is not preferred in terms of legitimate concerns over excessive vertical height growth, long fracture fluid cleanup times, lack of expertise and cost. This research study was carried out to understand the various damage mechanisms affecting the Oriskany wells, with a focus on gas storage wells. We then developed a dataset of reservoir properties, rock properties and fracture treatment data for Oriskany based on a complete literature review and calculations from a sonic log. Parametrical studies were carried out to investigate the effect of type of fracture fluids, injection rate, types of proppant, treatment volume, reservoir pressure and treatment schedule on fracture geometries in the Oriskany formation. Based on the results, we developed new stimulation methods that lead to increased well deliverability, fracture height containment, and higher average fracture conductivity. This new understanding and knowledge help in practicing engineers design better treatments in stimulating Oriskany wells.
Biogas Combustion in Premixed Flames or Electrochemical Oxidation in SOFC: Exergy and Emission Comparison
Authors: Quesito Francesco , Santarelli Massimo , Leone Pierluigi , Aggarwal Suresh K.
Published: March 2013

In the future energy pathway, characterized by flexibility of technologies and fuels, biogas could represent an alternative to conventional natural gas in feeding multiple types of technologies, both traditional thermal machines (chemical reactions), and innovative electrochemical generators such as fuel cells (electrochemical reactions). To compare the two pathways of energy production, two criteria are considered: (a) environmental analysis (emissions) and (b) exergy analysis. The results of the environmental and exergy comparison are presented and discussed in case of two selected transformation processes: partially premixed flames (PPFs, for chemical processes) and solid oxide fuel cells (SOFCs, for electrochemical processes), for a range of operating conditions. From an environmental point of view, the PPF exhaust stream has significant traces of NOx and C2H2, which are precursors of atmosphere pollution, while the SOFC exhaust stream does not contain such chemical species due to the absence of combustion. From a exergy point of view, the utilisation of the biogas in form of electrochemical oxidation in a SOFC indicates significantly higher exergetic efficiency compared to the chemical oxidation in partially premixed flames.
On Laminar Magnetoconvection Flow in a Vertical Channel in the Presence of Heat Generation and Heat Absorption
Authors: Umavathi J. C. , Patil Mallikarjun B. , Narasimha Murthy S.
Published: March 2013

The problem of hydromagnetic fully developed laminar mixed convection flow in a vertical channel and asymmetric wall heating conditions in the presence of electrical conductivity effect is considered through proper choice of dimensionless variables. The governing with symmetric equations are developed and three types of thermal boundary conditions are presented. These boundary conditions are isothermal–isothermal, isoflux–isothermal, and isothermal–isoflux for the left–right walls of the channel respectively. The velocity field and the temperature field are obtained by perturbation series method which employs a perturbation parameter proportional to the Brinkman number. In addition, closed form expressions for reversal flow conditions at both the left–right channel walls are derived. Selected set of graphical results illustrating the effects of the various parameters involved in the problem including magnetic dissipation, heat generation or absorption, and the electrical conductivity on the velocity and temperature profiles as well as flow reversal situation are presented. The solutions obtained are also compared with that of results obtained by finite difference method.
ANFIS Modeling of Human Welder's Response to Three-Dimensional Weld Pool Surface in GTAW
Authors: Liu YuKang , Zhang WeiJie , Zhang YuMing
Published: March 2013

Understanding and modeling of the human welder's response to three-dimensional (3D) weld pool surface may help develop next generation intelligent welding machines and train welders faster. In this paper, human welder's adjustment on the welding current as a response to the 3D weld pool surface characterized by its width, length, and convexity is studied. An innovative vision system is used to real-time measure the specular 3D weld pool surface under strong arc in gas tungsten arc welding (GTAW). Experiments are designed to produce random changes in the welding speed resulting in fluctuations in the weld pool surface. Adaptive neuro-fuzzy inference system (ANFIS) is proposed to correlate the human welder's response to the 3D weld pool surface using three inputs including the weld pool width, length and convexity. The human welder's behavior is not only related to the 3D weld pool geometry but also relies on the welder's previous adjustment. In this sense, a four input ANFIS model adding the previous human welder's response as a model input is developed and compared with the fitted linear model. It is found that the proposed ANFIS model can derive a more accurate correlation between the human welder's responses and the weld pool geometry and help understand the nonlinear response of the human welder to 3D weld pool surfaces.
Resistance Spot Welding of Ultra-Thin Automotive Steel
Authors: Zhao YangYang , Zhang YanSong , Lai XinMin , Wang Pei-Chung
Published: March 2013

One of the major challenges in spot welding of ultra-thin gage steel (e.g., <0.6 mm) is the short cap life. Because of the elevated temperature developed at the electrode/sheet interface, the electrodes often require dressing or replacement within a fraction of the time when welding more traditional automotive gage steel (>0.75 mm). In this study, the method of inserting flexible strips between the electrode and workpiece in resistance spot welding of 0.4 mm thick galvanized SAE1004 steel sheet has been adopted in order to reduce electrode tip temperature and improve weld quality. The effect of the inserted strips on the Joule heat generation and temperature distribution has been analyzed analytically. Then, because of the difficulties in measuring the experimental electrode tip temperature, a finite element model has been employed to estimate temperature distributions within the weld zone. The effects of the process variables (i.e., strip material and thickness) on the cap temperature and weld quality were modeled. Experiments were also conducted to validate the modeling results. Test data and modeling results showed that the presence of the strip significantly facilitated weld initiation and growth and decreased the rate of electrode degradation. Of the materials investigated, the desirable strip for resistance spot welding 0.4 mm thick galvanized SAE1004 steel was determined to be 0.12 mm thick Cu55Ni45 alloy.
Cost Estimates of Cellulosic Ethanol Production: A Review
Authors: Zhang P. F. , Zhang Q. , Pei Z. J. , Wang D. H.
Published: March 2013

Increasing demands and concerns for reliable supply of liquid transportation fuels make it important to find alternatives to petroleum-based fuels. One such alternative is ethanol made from cellulosic biomass. Considerable investigations have been conducted to evaluate the viability of cellulosic ethanol production in several aspects (including cost competitiveness). Cost estimates of cellulosic ethanol production have been reported by many researchers in order to evaluate the economic viability of cellulosic ethanol production. However, the reported cost estimates in the literature have a large variation. The current literature contains limited reviews on the cost estimates of cellulosic ethanol production and mostly focused on some individual processes. This paper presents a literature review on the cost estimates of entire cellulosic ethanol production. It reviews the estimated costs for both the entire cycle (from planting to conversion) and individual processes for cellulosic ethanol production. It also covers factors that lead to variations among reported cost estimates.
Combined Effect of Temper and Hydrogen Embrittlement on Threshold for Hydrogen-Induced Fracture in Cr-Mo Steels
Authors: Shimazu Hidenori , Konosu Shinji , Tanaka Yoichi , Yuga Masao , Yamamoto Hiroshi , Ohtsuka Naotake
Published: March 2013

This paper presents the results of the research activities of the subcommittee on hydrogen embrittlement of the Japan Pressure Vessel Research Council (JPVRC). The combined effect of temper embrittlement and hydrogen embrittlement in Cr-Mo steels is discussed. It has been recognized that Cr-Mo steels used widely in the refining and petrochemical industry are quite susceptible to temper embrittlement. Although the synergistic relation between temper embrittlement and hydrogen embrittlement is a matter of major concern, studies regarding this subject are rarely encountered. Task group VIII (TG8) of the JPVRC conducted fracture toughness tests for three kinds of 2.25Cr-1Mo steels and 2.25Cr-1Mo-0.3 V steel. These steels were prepared by subjecting them to normalizing, tempering, and postweld heat treatments (PWHTs) which simulated actual conditions. Some specimens were embrittled by step cooling (Socal-1 treatment). It was found that the threshold for hydrogen-induced fracture was lowered when the specimen was exposed to pressurized hydrogen gas (15 MPa) for 48 h at 450 °C and there was no marked indication of the synergistic action concerning this embrittlement.
Fatigue Limit Prediction of the Matrix of 17-4PH Stainless Steel Based on Small Crack Mechanics
Authors: Nie Defu , Mutoh Yoshiharu
Published: March 2013

The experimentally obtained fatigue limit of high strength steel is generally a value reduced by inherent flaws, and such a value does not characterize the resistance of the matrix of high strength steel to cyclic loading. To investigate the fatigue limit of the matrix, fatigue tests of 17-4PH stainless steel were performed. 17-4PH stainless steel showed a distinct dual-stage S-N curve: one stage corresponding to high stress where crack initiated at the surface and another stage corresponding to low stress where crack initiated from the subsurface inclusion (Al2O3). Based on small crack mechanics, a model was proposed to predict the fatigue limit of the matrix of 17-4PH stainless steel and its validity has been discussed.
Modeling the Electrophoretic Separation of Short Biological Molecules in Nanofluidic Devices
Authors: Fayad Ghassan N. , Hadjiconstantinou Nicolas G.
Published: March 2013

Via comparisons with rigid-rod and wormlike-chain Brownian dynamics (BD) simulations and the experimental results of Fu et al. (2006, “Molecular Sieving in Periodic Free-Energy Landscapes Created by Patterned Nanofilter Arrays,” Phys. Rev. Lett., 97(1), p. 018103), we demonstrate that, for the purposes of low-to-medium field electrophoretic separation, sufficiently short biomolecules can be modeled as point particles, with their orientational degrees of freedom accounted for using partition coefficients. This observation is used in the present work to build an efficient BD simulation method. Particular attention is paid to the model's ability to quantitatively capture experimental results using realistic values of all physical parameters.
Evanescent Wave-Based Flow Diagnostics
Authors: Kazoe Yutaka , Yoda Minami
Published: March 2013

Miniaturized flow systems have been developed for various applications, including integrated chemical analyses and thermal management of microelectronics. Understanding interfacial transport is important in designing and optimizing such flow systems, since surface effects become significant due to the large surface areas and small volumes at these length scales. Recently, various near-wall flow diagnostic techniques have been developed based on evanescent-wave illumination. Since evanescent waves only illuminate the fluid in the region over the first few hundred nanometers next to the wall, these techniques have much better spatial resolution than conventional methods based on epifluorescence microscopy. This paper presents recent advances in evanescent wave-based flow diagnostics using fluorescent tracers, including evanescent-wave particle velocimetry applied to flows driven by both pressure and voltage gradients and evanescent-wave fluorescence, which has been used to measure near-wall liquid temperature and pH fields, as well as the surface charge, or wall ζ-potential, distributions.
Simulation of Surface Reactions and Multiscale Transport Processes in a Composite Anode Domain Relevant for Solid Oxide Fuel Cells
Authors: Yuan Jinliang , Yang Guogang , Sunden Bengt
Published: March 2013

There are various transport phenomena (gas-phase species, heat, and momentum) occurring at different length scales in anode-supported solid oxide fuel cells (SOFCs), which are strongly affected by catalytic surface reactions at active triple-phase boundaries (TPBs) between the void space (for gas), Ni (catalysts for electrons), and YSZ (an electrolyte material for ions). To understand the multiscale chemical-reacting transport processes in the cell, a three-dimensional numerical calculation approach (the computational fluid dynamics (CFD) method) is further developed and applied for a composite domain including a porous anode, fuel gas flow channel, and solid interconnect. By calculating the rate of microscopic surface-reactions involving the surface-phase species, the gas-phase species/heat generation and consumption related to the internal reforming reactions have been identified and implemented. The applied microscopic model for the internal reforming reactions describes the adsorption and desorption reactions of six gas-phase species and surface reactions of 12 surface-adsorbed species. The predicted results are presented and analyzed in terms of the gas-phase species and temperature distributions and compared with those predicted by employing the global reaction scheme for the internal reforming reactions.
Fluid-Structure Interaction Analysis of Pulsatile Blood Flow and Heat Transfer in Living Tissues During Thermal Therapy
Authors: Mohamed AlAmiri Abdalla
Published: March 2013

The current numerical investigation tackles the fluid-structure interaction in a blood vessel subjected to a prescribed heating scheme on tumor tissues under thermal therapy. A pulsating incompressible laminar blood flow was employed to examine its impact on the flow and temperature distribution within the blood vessel. In addition, the arterial wall was modeled using the volume-averaged porous media theory. The motion of a continuous and deformable arterial wall can be described by a continuous displacement field resulting from blood pressure acting on the tissue. Moreover, discretization of the transport equations was achieved using a finite element scheme based on the Galerkin method of weighted residuals. The numerical results were validated by comparing them against documented studies in the literature. Three various heating schemes were considered: constant temperature, constant wall flux, and a step-wise heat flux. The first two uniform schemes were found to exhibit large temperature variation within the tumor, which might affect the surrounding healthy tissues. Meanwhile, larger vessels and flexible arterial wall models render higher variation of the temperature within the treated tumor, owing to the enhanced mixing in the vicinity of the bottom wall.