bluuebunny/crossref_metadata_2025 huggingface dataset:
High‐risk epithelial ovarian cancer patients for hereditary ovarian cancer
Authors: Chirasophon Seksit , Manchana Tarinee , Teerapakpinyo Chinachote
Published: February 2017

Aim

Risk assessment to identify patients at risk for hereditary ovarian cancer is important. The objectives of this study were to evaluate the frequency of high‐risk epithelial ovarian cancer (EOC) patients and the frequency of germline mutation in these patients.

Methods

A total of 335 patients with histologically confirmed non‐mucinous EOC were included. High‐risk patients were defined as patients who had: (i) significant family history of breast/ovarian/colorectal/endometrial cancers; (ii) synchronous breast/endometrial/colorectal cancer; or (iii) high‐grade serous carcinoma. Germline mutation was evaluated by Next Generation Sequencing system with the 27‐genes panel.

Results

A total of 94 patients (28.1%) were high‐risk patients, 5.1% had significant family history of cancers, 4.2% had synchronous primary cancers, and 22.1% had high‐grade serous carcinoma. Germline mutation was detected in 10 of 35 patients (28.6%). Six germline mutations (17.1%) occurred in homologous recombination (HR) genes; these included three (8.6%) in BRCA1, one (2.9%) in BRCA2, and two (5.7%) in other HR genes (CHEK2 and RAD1C). Three patients (8.6%) had MMR gene mutations (one MLH1 and two MSH2) and one patient (2.9%) had other gene mutation (MUTYH). Of the 10 patients with germline mutation, 40% of patients had no significant family history of cancer.

Conclusion

Up to 30% of EOC patients had risk factors for hereditary ovarian cancer. Germline mutation was identified in 28.6% of patients (11.4% BRCA mutation, 5.7% other HR genes mutation, 8.6% MMR mutation, and 2.9% mutation in other gene). The high cost of genetic testing is an important barrier. Selected patients with high‐risk factors might be initially considered for genetic testing in a limited‐resource setting.
High serum progesterone associated with infertility in a woman with nonclassic congenital adrenal hyperplasia
Authors: Kawarai Yoshimasa , Ishikawa Hiroshi , Segawa Tomoya , Teramoto Shokichi , Tanaka Tomoaki , Shozu Makio
Published: February 2017

Nonclassic congenital adrenal hyperplasia (NCAH) is an autosomal‐recessive disorder caused by 21‐hydroxylase deficiency and manifests as hirsutism and oligomenorrhea due to excess adrenal androgen and progesterone. We report a case of a woman with NCAH who showed continuous high serum progesterone levels in the follicular phase associated with impaired folliculogenesis. NCAH was diagnosed based on high 17‐hydroxyprogesterone levels after rapid adrenocorticotropic hormone loading, and three heterozygous missense mutations in CYP21A2, encoding 21‐hydroxylase, were identified. Recurrent failure of in vitro fertilization programs occurred because of empty follicles and preterm rupture of leading follicles, and vaginal stenosis with a hypoplastic cervix. Glucocorticoid administration normalized serum progesterone levels, restored folliculogenesis, and stretched the vaginal wall, which contributed to the success of the in vitro fertilization program. The patient delivered at term following blastocyst transfer. Correction of hyperandrogenism and high progesterone levels using glucocorticoids may improve fertility in women with NCAH.
Risk factors for central serous chorioretinopathy in pregnant Japanese women
Authors: Morikawa Mamoru , Cho Kazutoshi , Kojima Takashi , Chiba Kentaro , Ishikawa Satoshi , Umazume Takeshi , Nakagawa Kinuko , Yamada Takashi , Yamada Takahiro , Minakami Hisanori
Published: February 2017

Aim

This study was performed to determine risk factors for central serous chorioretinopathy (CSC) in pregnant women.

Methods

This retrospective observational study was performed in a cohort of all 1881 women giving birth at a single center. The hospital database was searched to abstract all women diagnosed with pre‐eclampsia (PE) as well as those visiting the eye clinic during the current pregnancy. Medical chart review was performed in all women diagnosed with CSC and PE.

Results

PE developed in 73 (3.9%) women, six (8.2%) of whom visited the eye clinic for problems occurring in the current pregnancy; 47 of 1808 (2.6%) women without PE visited the eye clinic (P  = 0.015). Four women were identified as having developed CSC after onset of PE, and none of those without PE developed CSC (5.5% [4/73] vs 0.0% [0/1808], respectively, P <  0.0001). Stepwise regression analysis selected four risk factors for CSC: hematocrit value > 38.0% (odds ratio [OR], 22.9; 95% confidence interval [CI], 2.12–247), serum creatinine > 0.7 mg/dL (OR, 21.7; 95%CI, 1.12–422), time interval from diagnosis of PE until delivery > 14 days (OR, 20.0; 95%CI, 1.87–214), and urine protein : creatinine ratio (mg/mg) > 4.5 (OR, 15.7; 95%CI, 0.81–304). Hematocrit value > 38.0% was finally identified as the only independent risk factor (OR, 22.9; 95%CI, 2.12–1716) for CSC in PE women.

Conclusion

CSC was likely to occur in PE women, especially in those with hemoconcentration as a result of plasma leakage from the circulating blood due to increased vascular permeability.
Effect of zinc sulfate supplementation on premenstrual syndrome and health‐related quality of life: Clinical randomized controlled trial
Authors: Siahbazi Shiva , Behboudi‐Gandevani Samira , Moghaddam‐Banaem Lida , Montazeri Ali
Published: February 2017

Aim

The purpose of study was to assess the effect of zinc sulfate (ZS) supplementation on premenstrual syndrome (PMS) and health‐related quality of life (QoL).

Methods

This was a double‐blind randomized and placebo‐controlled trial using the parallel technique conducted between June 2013 and May 2014. A total of 142 women (age, 20–35 years) with PMS were allocated to either the ZS or placebo group. The women in the intervention group received ZS 220‐mg capsules (containing 50 mg elemental zinc) from the 16th day of the menstrual cycle to the second day of the next cycle. Data were collected using the Premenstrual Symptoms Screening Tool (PSST) and 12‐item Short‐Form Health Survey Questionnaire.

Result

The prevalence of moderate to severe PMS in the ZS group significantly decreased throughout the study period (9.5% in the first, 6% in the second and 2.6% in the third month of the study, P < 0.001), but in the control placebo group this reduction was seen only in the first month of the study (14.2% in the first, 13.7% in the second and 13.5% in the third month, P = 0.08). Also, ZS improved the PSST component scores throughout the study period. The mean scores of QoL in physical and mental components were significantly improved in the ZS intervention group. However, the differences were statistically significant only 3 months after the intervention.

Conclusion

Zinc sulfate, as a simple and inexpensive treatment, was associated with improvement of PMS symptoms and health‐related QoL. Additional studies are warranted to confirm these findings.
Identification of Mungbean yellow mosaic Indian virus Associated with Tomato Leaf Curl Betasatellite Infecting Phaseolus vulgaris in Oman
Authors: Shahid Muhammad S. , Briddon Rob W. , Al‐Sadi Abdullah M.
Published: February 2017

Kidney bean (Phaseolus vulgaris) plants exhibiting foliar yellow mosaic symptoms and some leaf crumpling were identified in the Al Batinah region of Oman. Rolling circle amplification and polymerase chain reaction identified a bipartite begomovirus (family Geminiviridae) and a betasatellite in association with the symptomatic plants. Analysis of full‐length sequences showed the virus to be Mungbean yellow mosaic Indian virus (MYMIV) and the betasatellite Tomato leaf curl betasatellite (ToLCB). This is the first identification of a legume‐adapted begomovirus in Oman and the first identification of MYMIV in association with the betasatellite ToLCB. The isolate of MYMIV from Oman shows the greatest levels of sequence identity to isolates occurring in South Asia and South‐East Asia, suggesting that the virus has only recently been introduced. The significance of these findings is discussed.
Legal Mobilization within the Bureaucracy: Disability Rights and the Implementation of Antidiscrimination Law in Sweden
Authors: Lejeune Aude
Published: February 2017

This article argues that the analysis of legal mobilization needs to give more attention to the state and its relationship with social movements in order to examine how the state either sustains social movements’ demands or is a field of contention for those demands. Focusing on how disability bureaucrats and activists mobilize antidiscrimination law in Sweden, this article shows that two main factors shape legal mobilization within the bureaucracy and alter the state's ability to become a legal mobilization actor: (1) the institutional relationships between social movement organizations and government agencies and (2) the profiles and careers of bureaucrats and activists. It concludes by suggesting several lines for further research on law and social movements in nonpluralist countries.
Comparative glandular trichome transcriptome‐based gene characterization reveals reasons for differential (−)‐menthol biosynthesis in Mentha species
Authors: Akhtar Md Qussen , Qamar Nida , Yadav Pallavi , Kulkarni Pallavi , Kumar Ajay , Shasany Ajit Kumar
Published: February 2017

The genes involved in menthol biosynthesis are reported earlier in Mentha × piperita. But the information on these genes is not available in Mentha arvensis. To bridge the gap in knowledge on differential biosynthesis of monoterpenes leading to compositional variation in the essential oil of these species, a comparative transcriptome analysis of the glandular trichome (GT) was carried out. In addition to the mevalonic acid (MVA) and methylerythritol phosphate (MEP) pathway genes, about 210 and 196 different terpene synthases (TPSs) transcripts were identified from annotation in M. arvensis and M. × piperita, respectively, and correlated to several monoterpenes present in the essential oil. Six isoforms of (−)‐menthol dehydrogenases (MD), the last enzyme of the menthol biosynthetic pathway, were identified, cloned and characterized from the transcriptome data (three from each species). Varied expression levels and differential enzyme kinetics of these isoforms indicated the nature and composition of the product, as these isoforms generate both (−)‐menthol and (+)‐neomenthol from (−)‐menthone and converts (−)‐menthol to (−)‐menthone in the reverse reaction, and hence together determine the quantity of (−)‐menthol in the essential oil in these two species. Several genes for high value minor monoterpenes could also be identified from the transcriptome data.
The influence of adrenergic stimulation on sex differences in left ventricular twist mechanics
Authors: Williams Alexandra M. , Shave Rob E. , Cheyne William S. , Eves Neil D.
Published: February 2017

Key points

Sex differences in left ventricular (LV) mechanics occur during acute physiological challenges; however, it is unknown whether sex differences in LV mechanics are fundamentally regulated by differences in adrenergic control.

Using two‐dimensional echocardiography and speckle tracking analysis, this study compared LV mechanics in males and females matched for LV length during post‐exercise ischaemia (PEI) and β1‐adrenergic receptor blockade.

Our data demonstrate that while basal rotation was increased in males, LV twist was not significantly different between the sexes during PEI. In contrast, during β1‐adrenergic receptor blockade, LV apical rotation, twist and untwisting velocity were reduced in males compared to females.

Significant relationships were observed between LV twist and LV internal diameter and sphericity index in females, but not males.

These findings suggest that LV twist mechanics may be more sensitive to alterations in adrenergic stimulation in males, but more highly influenced by ventricular structure and geometry in females.

Sex differences in left ventricular (LV) mechanics exist at rest and during acute physiological stress. Differences in cardiac autonomic and adrenergic control may contribute to sex differences in LV mechanics and LV haemodynamics. Accordingly, this study aimed to investigate sex differences in LV mechanics with altered adrenergic stimulation achieved through post‐handgrip‐exercise ischaemia (PEI) and β1‐adrenergic receptor (AR) blockade. Twenty males (23 ± 5 years) and 20 females (22 ± 3 years) were specifically matched for LV length (males: 8.5 ± 0.5 cm, females: 8.2 ± 0.6 cm, P = 0.163), and two‐dimensional speckle‐tracking echocardiography was used to assess LV structure and function at baseline, during PEI and following administration of 5 mg bisoprolol (β1‐AR antagonist). During PEI, LV end‐diastolic volume and stroke volume were increased in both groups (P < 0.001), as was end‐systolic wall stress (P < 0.001). LV twist and apical rotation were not altered from baseline or different between the sexes; however, basal rotation increased in males (P = 0.035). During β1‐AR blockade, LV volumes were unchanged but blood pressure and heart rate were reduced in both groups (P < 0.001). LV apical rotation (P = 0.036) and twist (P = 0.029) were reduced in males with β1‐AR blockade but not females, resulting in lower apical rotation (males: 6.8 ± 2.1 deg, females: 8.8 ± 2.3 deg, P = 0.007) and twist (males: 8.6 ± 1.9 deg, females: 10.7 ± 2.8 deg, P = 0.008), and slower untwisting velocity (males: 68.2 ± 22.1 deg s−1, females: 82.0 ± 18.7 deg s−1, P = 0.046) compared to females. LV twist mechanics are reduced in males compared to females during reductions to adrenergic stimulation, providing preliminary evidence that LV twist mechanics may be more sensitive to adrenergic control in males than in females.
Detailed Analysis and Description of Grinding Wheel Topographies
Authors: Weiß Markus , Klocke Fritz , Barth Sebastian , Rasim Matthias , Mattfeld Patrick
Published: February 2017

In this paper, an innovative approach for the description of the functional properties of a grinding wheel surface is discussed. First, the state of the art in the description of grinding wheel topographies is summarized. Furthermore, the fundamentals for a new approach for the quantitative description of grinding wheel topographies are provided. In order to analyze the functional properties of a grinding wheel's topography depending on its specification, grinding experiments were carried out. For the experimental investigations vitrified, synthetic resin bonded and electroplated grinding wheels with varied compositions were analyzed. During the experiments, the topographies of the investigated grinding wheels have been analyzed by means of the topotool in detail. The developed software tool allows a detailed description of the kinematic cutting edges depending on the grinding process parameters and the grinding wheel specification. In addition to the calculation of the number of kinematic cutting edges and the area per cutting edge, a differentiation of the cutting edge areas in normal and tangential areas of the grinding wheel's circumferential direction is implemented. Furthermore, the topotool enables to analyze the kinematic cutting edges shape by calculating the angles of the grain in different directions. This enables a detailed analysis and a quantitative comparison of grinding wheel topographies related to different grinding wheel specifications. In addition, the influence of the dressing process and wear conditions to the grinding wheel topography can be evaluated. The new approach allows a better characterization of the contact conditions between grinding wheel and workpiece. Hence, the impact of a specific topography on the grinding process behavior, the generated grinding energy distribution, and the grinding result can be revealed.
Are Non-Newtonian Effects Important in Hemodynamic Simulations of Patients With Autogenous Fistula?
Authors: Javid Mahmoudzadeh Akherat S. M. , Cassel Kevin , Boghosian Michael , Dhar Promila , Hammes Mary
Published: February 2017

Given the current emphasis on accurate computational fluid dynamics (CFD) modeling of cardiovascular flows, which incorporates realistic blood vessel geometries and cardiac waveforms, it is necessary to revisit the conventional wisdom regarding the influences of non-Newtonian effects. In this study, patient-specific reconstructed 3D geometries, whole blood viscosity data, and venous pulses postdialysis access surgery are used as the basis for the hemodynamic simulations of renal failure patients with native fistula access. Rheological analysis of the viscometry data initially suggested that the correct choice of constitutive relations to capture the non-Newtonian behavior of blood is important because the end-stage renal disease (ESRD) patient cohort under observation experience drastic variations in hematocrit (Hct) levels and whole blood viscosity throughout the hemodialysis treatment. For this purpose, various constitutive relations have been tested and implemented in CFD practice, namely Quemada and Casson. Because of the specific interest in neointimal hyperplasia and the onset of stenosis in this study, particular attention is placed on differences in nonhomeostatic wall shear stress (WSS) as that drives the venous adaptation process that leads to venous geometric evolution over time in ESRD patients. Surprisingly, the CFD results exhibit no major differences in the flow field and general flow characteristics of a non-Newtonian simulation and a corresponding identical Newtonian counterpart. It is found that the vein's geometric features and the dialysis-induced flow rate have far greater influence on the WSS distribution within the numerical domain.
Evaluation of Hemodynamics in a Prestressed and Compliant Tapered Femoral Artery Using an Optimization-Based Inverse Algorithm
Authors: Banerjee Rupak K. , D'Souza Gavin A. , Paul Anup K. , Das Ashish
Published: February 2017

The important factors that affect the arterial wall compliance are the tissue properties of the arterial wall, the in vivo pulsatile pressure, and the prestressed condition of the artery. It is necessary to obtain the load-free geometry for determining the physiological level of prestress in the arterial wall. The previously developed optimization-based inverse algorithm was improved to obtain the load-free geometry and the wall prestress of an idealized tapered femoral artery of a dog under varying arterial wall properties. The compliance of the artery was also evaluated over a range of systemic pressures (72.5–140.7 mmHg), associated blood flows, and artery wall properties using the prestressed arterial geometry. The results showed that the computed load-free outer diameter at the inlet of the tapered artery was 6.7%, 9.0%, and 12% smaller than the corresponding in vivo diameter for the 25% softer, baseline, and 25% stiffer arterial wall properties, respectively. In contrast, the variations in the prestressed geometry and circumferential wall prestress were less than 2% for variable arterial wall properties. The computed compliance at the inlet of the prestressed artery for the baseline arterial wall property was 0.34%, 0.19%, and 0.13% diameter change/mmHg for time-averaged pressures of 72.5, 104.1, and 140.7 mmHg, respectively. However, the variation in compliance due to the change in arterial wall property was less than 6%. The load-free and prestressed geometries of the idealized tapered femoral artery were accurately (error within 1.2% of the in vivo geometry) computed under variable arterial wall properties using the modified inverse algorithm. Based on the blood-arterial wall interaction results, the arterial wall compliance was influenced significantly by the change in average pressure. In contrast, the change in arterial wall property did not influence the arterial wall compliance.
Uncertainty Quantification in a Patient-Specific One-Dimensional Arterial Network Model: EnKF-Based Inflow Estimator
Authors: Arnold Andrea , Battista Christina , Bia Daniel , German Yanina Zócalo , Armentano Ricardo L. , Tran Hien , Olufsen Mette S.
Published: February 2017

Successful clinical use of patient-specific models for cardiovascular dynamics depends on the reliability of the model output in the presence of input uncertainties. For 1D fluid dynamics models of arterial networks, input uncertainties associated with the model output are related to the specification of vessel and network geometry, parameters within the fluid and wall equations, and parameters used to specify inlet and outlet boundary conditions. This study investigates how uncertainty in the flow profile applied at the inlet boundary of a 1D model affects area and pressure predictions at the center of a single vessel. More specifically, this study develops an iterative scheme based on the ensemble Kalman filter (EnKF) to estimate the temporal inflow profile from a prior distribution of curves. The EnKF-based inflow estimator provides a measure of uncertainty in the size and shape of the estimated inflow, which is propagated through the model to determine the corresponding uncertainty in model predictions of area and pressure. Model predictions are compared to ex vivo area and blood pressure measurements in the ascending aorta, the carotid artery, and the femoral artery of a healthy male Merino sheep. Results discuss dynamics obtained using a linear and a nonlinear viscoelastic wall model.
Natural Convection Heat Transfer From a Short or Long, Solid or Hollow Horizontal Cylinder Suspended in Air or Placed on Ground
Authors: Acharya Swastik , Dash Sukanta K
Published: February 2017

Numerical simulations have been conducted to study natural convection heat transfer from solid or hollow cylinders in the laminar range of Ra spanning from 104 to 108 for L/D in the range of 0.05≤(L/D)≤20. Interesting flow structures around the thin hollow cylinder have been observed for small and large L/D. It has been found that the average Nu for solid or hollow horizontal cylinders in air is marginally higher than when they are on ground for the entire range of L/D and Ra limited up to 107. Up to a Ra of 107 Nu for a solid cylinder in air is higher than that of Nu for a hollow cylinder in air but when Ra exceeds 107 Nu for a hollow cylinder is marginally higher than that of the solid cylinder until an L/D of 0.2. When, L/D rises beyond 0.2 the situation reveres causing Nu for a solid cylinder to be again higher than that of the hollow cylinder when suspended in air. A solid cylinder on ground has higher Nu compared to that of a hollow cylinder on ground up to a Ra of 106. However, for higher Ra of 108 a hollow cylinder on ground has higher Nu compared to that of a solid cylinder on ground until an L/D of 5 and after that the situation reverses again.
A Simple Physics-Based Model for Particle Rebound and Deposition in Turbomachinery
Authors: Bons J. P. , Prenter R. , Whitaker S.
Published: February 2017

A new model is proposed for predicting particle rebound and deposition in environments relevant to gas turbine engines. The model includes the following physical phenomena: elastic deformation, plastic deformation, adhesion, and shear removal. It also incorporates material property sensitivity to temperature and tangential-normal rebound velocity cross-dependencies observed in experiments. The model is well-suited for incorporation in computational fluid dynamics (CFD) simulations of complex gas turbine flows due to its algebraic (explicit) formulation. Model predictions are compared to coefficient of restitution data available in the open literature as well as deposition results from two different high-temperature turbine deposition facilities. While the model comparisons with experiments are in many cases promising, several key aspects of particle deposition remain elusive. The simple phenomenological nature of the model allows for parametric dependencies to be evaluated in a straightforward manner. It is hoped that this feature of the model will aid in identifying and resolving the remaining stubborn holdouts that prevent a universal model for particle deposition.
Experimental Investigation of Cavitation Behind a Circular Cylinder in Cross-Flow
Authors: Kumar Pankaj , Bakshi Shamit , Chatterjee Dhiman
Published: February 2017

Cavitation behind a circular cylinder is studied with the aid of highly time-resolved images at a constant Reynolds number of 64,000. Apart from recording the overall cavitation activity behind the cylinder, the study also delves into the dynamics of individual cavities. The length of cavity scales with cavitation number and this scaling is similar to the existing results obtained in flow regimes different from that presented here. Dynamics of individual cavities show distinct phases of cavity formation, growth, and collapse. At lower cavitation numbers, cavity collapse was followed by a rebounce. Variation of area normalized by the length of cavity shows self similarity in the growth phase of cavities for different cavitation numbers. Thus, the cavity length is the suitable length scale for dynamics of cavities, at least for the growth phase. The cavity lifetime scales inversely with the square of cavitation number. Dynamics of individual small cavity captured at higher frame rates was found to be similar to that of an isolated bubble. In this case, a rapid collapse follow a more gradual expansion phase, unlike that shown by larger cavities.
Thermal Hydraulic Modeling and Analysis of Fusion Reactors Plasma Facing Components Using Alumina Nanofluids
Authors: Genco Filippo , Genco Giacinto
Published: February 2017

Damage to plasma facing components (PFC) due to high intense energy deposition during tokamak plasma instabilities is still considered one of the most serious and unresolved problem for the fusion reactors. Key plasma facing components as the divertor and the entire first wall during off-normal operations are generally subjected to high rate of deposition of energy, neutrons, and radiation leading generally to structural catastrophic failures including burnout of coolant tubes. The use of alumina nanofluids applied to future fusion reactors is proposed to, at least, mitigate some of the problems described providing better thermal performance during off-normal events. A 1D heat transfer model using the characteristics of alumina nanoparticles dispersed in common water is presented. Heat transfer of alumina nanofluid is modeled. Results obtained are critically compared with other well-known computer packages and experiments used to predict the coolant heat removal capabilities during longer quasi-steady state plasma instabilities events. Enhancements produced by the use of alumina nanoparticles are evident. Comparisons with both pure water and swirl tape inserts are carried out and critical heat flux (CHF) conditions are predicted showing good agreement with both published numerical and experimental data.
Numerical Simulation of Frosting on Fin-and-Tube Heat Exchanger Surfaces
Authors: Wu Xiaomin , Ma Qiang , Chu Fuqiang
Published: February 2017

Frost on heat exchanger fin surfaces increases the thermal resistance and blocks the air flow passages, which reduce the system energy efficiency. Therefore, investigations of frost formation especially simulations of frosting on the heat exchanger surfaces are essential for designing heat exchangers that operate with frosting. In this paper, the frost growth and densification processes on fin-and-tube heat exchanger surfaces are numerically investigated using a mass transfer model implemented as a user-defined function (UDF) in fluent. The model predicts the frost distributions on the heat exchanger surfaces, the temperature distributions, and the air flow pressure drop. The results show that the frost is thicker and the frost density is higher on the fin surfaces on the windward side near the tubes, while the frost is thinner and the density is lower near the inlet. Very little frost appears in the tube wake region. Frost on the fin-and-tube heat exchanger surfaces restricts the airflow and about doubles the pressure drop after frosting for 50 min. The simulated frost distributions and pressure drops are in good agreement with experimental data, which means that the frosting model can be used to predict frost layer growth on heat exchanger surfaces and the resulting airflow resistance.
Thermal Performance of Biomass-Fired Steam Power Plant
Authors: Ghenai Chaouki , Amine Hachicha Ahmed
Published: February 2017

This paper presents results on the performance of 10 MW biomass-fired steam power plant. The main objective is to test the performance of the power plant using different type of biomass fuels: bagasse, corn stover, forest residues, and urban wood residues. The biomass fuel was mixed with sub-bituminous coal with fractions of 0–100%. The effect of excess combustion air, flue gas temperature, and the parasitic loads on the power plant performance was investigated. The output results from the heat and mass balance analysis include the monthly and annual electrical power generated, capacity factor (CF), boiler efficiency (BE), thermal efficiency, and gross and net heat rate. The results show a slightly decrease (1.7%) of the annual energy production when the biomass fractions increase from 6% to 100% but a substantial decrease of the CO2 equivalent emissions. A decrease of the excess combustion air from 25% to 5% will increase the boiler and thermal efficiencies and the annual energy output by 2%. This is mainly due to the reduction of the dry flue gas losses (DFGLs) with the reduction of the excess combustion air. A reduction of the parasitic loads from 10% to 2% will increase the power plant performance by 9%. This can be achieved by using more efficient pumps, fans, and conveyors in the power plant. A reduction of the flue gas temperature from 480 °F to 360 °F increases the power plant performance by 4.4% due to the reduction of the dry flue gas losses.
Adaptive Control of Linear Time-Varying Interval Systems
Authors: Dabbous Tayel
Published: February 2017

In this paper, we consider the adaptive control problem for a class of systems governed by linear time-varying interval differential equations having unknown (interval) parameters. Using the fact that system output posses lower and upper bounds, we have converted the interval differential equation into two sets of ordinary differential equations that describe the behavior of lower and upper bounds of system output. With this approach, interval analysis could be replaced by real analysis, and hence, adaptive control of interval systems can be treated as an ordinary adaptive control problem. Using variation arguments, we have developed the necessary conditions of optimality for the equivalent adaptive control problem. Finally, we present a numerical example to illustrate the effectiveness of the proposed (interval) control scheme.
Experimental Study on the Effect of Number of Bubble Occurrences on Tip Vortex Cavitation Noise Scaling Law
Authors: Park Jisoo , Seong Woojae
Published: February 2017

A novel scaling law for the tip vortex cavitation (TVC) noise was determined, employing the Rankine vortex model, the Rayleigh–Plesset equation, the lifting surface theory, the boundary layer effect, and the number of bubbles generated per unit time (N0). All terms appearing in the final derived scaling law are well known three-dimensional (3D) lifting surface parameters, except for N0. In this study, the dependence of N0 with inflow velocity and hydrofoil dimension is investigated experimentally while trying to retain the same TVC patterns among different experimental conditions. Afterward, the effect of N0 on the TVC noise is analyzed. Optimal TVC observation conditions are determined from consideration of cavitation number and Reynolds number of two comparable conditions. Two geometrically scaled hydrofoils are concurrently placed in a cavitation tunnel for the hydrofoil size variation experiment. Wall effects and flow field interaction are prevented with the aid of computational fluid dynamics. Images taken with a high‐speed camera are used to count N0 by visual inspection. The noise signals at all conditions are measured and an acoustic bubble counting technique, to supplement visual counting, is devised to determine N0 acoustically from the measured noise data. The broad-band noise scaling law incorporating N0 and the International Towing Tank Conference (ITTC) cavitation noise estimation rule for hydrofoil are both applied to estimate the TVC noise level for comparison with the measured noise level. The noise level estimated by the broad-band noise scaling law accounting for the acoustically estimated N0 gives the best agreement with the measured noise level.
Prediction of Interfacial Surface Energy and Effective Fracture Energy From Contaminant Concentration in Polymer-Based Interfaces
Authors: Yavas Denizhan , Bastawros Ashraf F.
Published: February 2017

The principals of interfacial fracture mechanics and modified Gibbs adsorption equation are utilized to provide a predictive correlation for the macroscopic (effective) fracture toughness of polymer-based adhesive interfaces, exposed to varying level of contaminant concentration. The macroscopic fracture toughness measurement by double cantilever beam test exhibits a progressive deterioration with the increase of the contaminant surface concentration. The associated variation of fracture surface morphology exhibits ductile-to-brittle failure transition, caused by the contamination-induced suppression of plastic deformation within the adhesive layer. The corresponding intrinsic interfacial surface energy is extracted by finite-element simulation, employing surface-based cohesive elements. The modified Gibbs adsorption equation is utilized to correlate the contamination-induced degradation of the interfacial surface energy as a function of contaminant surface concentration. Interfacial fracture mechanics principals are applied to extend the correlation to the macroscopic fracture toughness of the interface. With additional examination of other systems, the proposed correlation may provide the basis for nondestructive evaluation of bond line integrity, exposed to different levels of contaminant.
A New Design of Horizontal Electro-Vibro-Impact Devices
Authors: Nguyen Van-Du , Nguyen Huu-Cong , Ngo Nhu-Khoa , La Ngoc-Tuan
Published: February 2017

This paper presents a development in design, mathematical modeling, and experimental study of a vibro-impact moling device, which was invented by the author before. A vibratory unit deploying electromechanical interactions of a conductor with oscillating magnetic field has been realized and developed. The combination of resonance in an RLC circuit including a solenoid is found to create a relative oscillatory motion between the metal bar and the solenoid. This results in impacts of the solenoid on an obstacle block, which causes the forward motion of the system. Compared to the former model which employs impact from the metal bar, the improved rig can offer a higher progression rate of six times when using the same power supply. The novel geometrical arrangement allows for future optimization in terms of system parametric selection and adaptive control. This implies a very promising deployment of the mechanism in ground moling machines as well as other self-propelled mobile systems. In this paper, insight to the design development based on physical and mathematical models of the rig is presented. The coupled electromechanical equations of motion then are solved numerically, and a comparison between experimental results and numerical predictions is presented.
The Powerful Method of Characteristics Module in Advanced Neutronics Lattice Code KYLIN-2
Authors: Chai Xiaoming , Tu Xiaolan , Lu Wei , Lu Zongjian , Yao Dong , Li Qing , Wu Wenbin
Published: February 2017

Due to powerful geometry treatment capability, method of characteristics (MOC) currently becomes one of the best method to solve neutron transport equation. In MOC method, boundary condition treatment, complex geometry representation, and advanced acceleration method are the key techniques to develop a powerful MOC code to solve complex problem. In this paper, we developed a powerful MOC module, which can treat different boundary conditions with two methods. For problems with special border shapes and boundary condition, such as rectangle, 1/8 of square, hexagon, 1/3 of hexagon, 1/6 of hexagon problems with reflection, rotation, and translation boundary condition, the MOC module adopts periodic tracking method, with which rays can return to start point after a certain distance. For problems with general border shapes, the MOC module uses ray prolongation method, which can treat arbitrary border shapes and boundary conditions. Meanwhile, graphic user interface based on computer aided design (CAD) software is developed to generate the geometry description file, in which geometry is represented by “lines and arcs” method. With the graphic user interface, the geometry and mesh can be described and modified correctly and fast. In order to accelerate the MOC transport calculation, the generalized coarse mesh finite difference (GCMFD) is used, which can use irregular coarse mesh diffusion method to accelerate the transport equation. The MOC module was incorporated into advanced neutronics lattice code KYLIN-2, which was developed by Nuclear Power Institute of China (NPIC) and used to simulate the assembly of current pressurized water reactor (PWR) and advanced reactors, to solve the transport equation with multigroup energy structure in cross sections database. The numerical results show that the KYLIN-2 code can be used to calculate 2D neutron transport problems in reactor accurately and fast. In future, the KYLIN-2 code will be released and gradually become the main neutron transport lattice code in NPIC.
Calculating Failure Pressure Under Different Failure Modes in the Roof-to-Shell of a Vaulted Tank
Authors: Ding Yuqi , Liu Jubao , Chen Zengtao , Qiu Feng , Lu Qifa
Published: February 2017

In this study, two failure modes, yield buckling of the compression ring section and strength failure in the roof-to-shell of the tank, have been proposed for a vertical vaulted tank. The failure criteria of the two failure modes in the roof-to-shell of vault tanks are established via finite element analysis of three tanks of 640 m3, 3200 m3, and 6800 m3 in volume. The finite element models are built with axisymmetric elements and spatial multi-elements. Based on the strength failure criterion, the failure pressure formula in the vaulted tank roof-to-shell is derived. The maximum relative error between the theoretical calculation and numerical simulation is 9.7%. Finally, we verify the strength failure criterion through a tank failure test; the maximum relative error between the test and theoretical calculation is 9.6%. The failure pressure of both failure modes has been compared and analyzed. The failure pressure of the yield buckling in the compression ring section is about 1.65 times that of the strength failure in the roof-to-shell of the tank.
Effects of Magnetic Field on the Phase Change Cells and the Formation of Ice Crystals in Biomaterials: Carrot Case
Authors: Liu Bin , Song Jianfei , Yao Zhaodn , Bennacer Rachid
Published: February 2017

In order to explore the effect of direct current (DC) and alternating current (AC) magnetic field (MF) on the biological (fruits and vegetables) phase transformation and ice crystal formation, we used carrot strips (0.5 × 0.5 × 1 cm3) and put them at low temperature control panel. The samples were frozen under AC and DC MF of 50 Hz with different intensities, i.e., 0, 0.46, 0.9, 1.8, 3.6, and 7.2 mT. The ice crystals formation during the process of cell freezing was observed and recorded using the optical microscope, and the beginning and ending time of the phase transformation with the corresponding temperatures were determined. The results show that the DC and AC MF situations compared to non-MF can decrease ice crystal volume and be more flocculent. The changes will reduce the cell membrane damage rate. The increase of magnetic field intensity delays the phase change time and leads to a shorter phase transition duration, a reduction in the cells’s lowest noncrystallization temperature is also observed. Such changes in thermal dynamic process and size elementary freezing (rapid formation of small ice crystals) reduce the damage to the quality of fruits and vegetables.
On the Stability of Planar Premixed Flames Under Nonadiabatic Conditions and Preferential Diffusion
Authors: Al-Sarairah Eman , Al-Hasanat Bilal , Hachicha Ahmed
Published: February 2017

In this paper, we provide a numerical study of the stability analysis of a planar premixed flame. The interaction of preferential diffusion and heat loss for a planar premixed flame is investigated using a thermodiffusive (constant density) model. The flame is studied as a function of three nondimensional parameters, namely, Damköhler number (ratio of diffusion time to chemical time), Lewis number (ratio of thermal to species diffusivity), and heat loss. A maximum of four solutions are identified in some cases, two of which are stable. The behavior of the eigenvalues of the linearized system of stabilty is also discussed. For low Lewis number, the heat loss plays a major role in stabilizing the flame for some moderately high values of Damköhler number. The results show the effect of increasing or decreasing Lewis number on adiabatic and nonadiabatic flames temperature and reaction rate as well as the range of heat loss at which flames can survive.
Evaluations of Molecular Dynamics Methods for Thermodiffusion in Binary Mixtures
Authors: Mozaffari Seyedeh H. , Srinivasan Seshasai , Ziad Saghir M.
Published: February 2017

The objective of this paper is to investigate the behavior of two well-known boundary-driven molecular dynamics (MD) approaches, namely, reverse nonequilibrium molecular dynamics (RNEMD) and heat exchange algorithm (HEX), as well as introducing a modified HEX model (MHEX) that is more accurate and computationally efficient to simulate the mass and heat transfer mechanism. For this investigation, the following binary mixtures were considered: one equimolar mixture of argon (Ar) and krypton (Kr), one nonequimolar liquid mixture of hexane (nC6) and decane (nC10), and three nonequimolar mixtures of pentane (nC5) and decane. In estimating the Thermodiffusion factor in these mixtures using the three methods, it was found that consistent with the findings in the literature, RNEMD predictions have the largest error with respect to the experimental data. Whereas, the MHEX method proposed in this work is the most accurate, marginally outperforming the HEX method. Most importantly, the computational efficiency of MHEX method is the highest, about 7% faster than the HEX method. This makes it more suitable for integration with multiscale computational models to simulate thermodiffusion in a large system such as an oil reservoir.
Electric Manipulation of Laminar Nonpremixed Counterflow Propane Flames
Authors: AL-Naeemy Ahmad M. Y. , Farraj Abdul Rahman D. , Kyritsis Dimitrios C. , Al-Khateeb Ashraf N.
Published: February 2017

The effect of the electric field on laminar nonpremixed counterflow propane flames was analyzed computationally. The computations were conducted using ANSYS fluent platform associated with a detailed kinetic mechanism. The mechanism was supplemented with a set of three reactions accounting for the consumption/production of three chemi-ions. It was established that the position of the flame could be only controlled through altering the intensity of the applied electric field. The effect of the applied electric field was included within the reactive flow equations via introducing two distinct terms: a body force term that accounts for the electric field effects on the momentum of the reactive mixture, and an extra diffusion term that accounts for the mobility charged species, namely ambipolar diffusion. This study clearly shows that electric force provides a potential for controlling the location of propane flames without affecting their structure.
Mechanical and Heat Transfer Performance Investigation of High Thermal Conductivity, Commercially Available Polymer Composite Materials for Heat Exchange in Electronic Systems
Authors: Rodgers Peter , Eveloy Valerie , Diana Antoine , Darawsheh Ismail , Almaskari Fahad
Published: February 2017

The thermal, mechanical, and morphological characteristics of three selected commercially available, injection-moldable, high thermal conductivity (20–32 W/m K), polyimide 66 (PA66) polymer composites from two vendors are characterized for possible heat exchange applications in electronic equipment. The fillers are found to consist of 10 μm diameter, 120–350 μm long fibers, made of carbon in two composites, and a hybrid combination of essentially carbon, oxygen, and silicon in the third composite. Fiber weight loading ranges from 63% to 69%. The hybrid, high-length fiber-reinforced material overall displays superior mechanical properties (i.e., ultimate tensile, flexural and impact strengths, and flexural modulus) compared with the other two carbon-filled composites. For the hybrid-filled and one carbon-filled material (both having a thermal conductivity of 20 W/m K), good agreement between mechanical property measurements and corresponding vendor data is obtained. For the material having the highest vendor-specified thermal conductivity (i.e., 32 W/m K) and weight filler fraction (i.e., 69%), mechanical properties are up to 37% lower than corresponding vendor data. The heat transfer rates of parallel plate, cross-flow air–water heat exchanger prototypes made of the three PA66 materials are comparable to that of an aluminum prototype having the same geometry. Based on the combined heat transfer and mechanical property characterization results, the hybrid, long fiber-filled PA66 polymer composite appears to have the best combination of mechanical and heat transfer characteristics, for potential use in electronics heat exchange applications.
Effect of Cross Aspect Ratio on Flow in Diverging and Converging Microchannels
Authors: Duryodhan V. S. , Singh Shiv Govind , Agrawal Amit
Published: February 2017

Aspect ratio is an important parameter in the study of flow through noncircular microchannel. In this work, three-dimensional numerical study is carried out to understand the effect of cross aspect ratio (height to width) on flow in diverging and converging microchannels. Three-dimensional models of the diverging and converging microchannels with angle: 2–14 deg, aspect ratio: 0.05–0.58, and Reynolds number: 130–280 are employed in the simulations with water as the working fluid. The effects of aspect ratio on pressure drop in equivalent diverging and converging microchannels are studied in detail and correlated to the underlying flow regime. It is observed that for a given Reynolds number and angle, the pressure drop decreases asymptotically with aspect ratio for both the diverging and converging microchannels. At small aspect ratio and small Reynolds number, the pressure drop remains invariant of angle in both the diverging and converging microchannels; the concept of equivalent hydraulic diameter can be applied to these situations. Onset of flow separation in diverging passage and flow acceleration in converging passage is found to be a strong function of aspect ratio, which has not been shown earlier. The existence of a critical angle with relevance to the concept of equivalent hydraulic diameter is identified and its variation with Reynolds number is discussed. Finally, the effect of aspect ratio on fluidic diodicity is discussed which will be helpful in the design of valveless micropump. These results help in extending the conventional formulae made for uniform cross-sectional channel to that for the diverging and converging microchannels.