期刊文献+
共找到66篇文章
< 1 2 4 >
每页显示 20 50 100
Quantification of irrigation water transport processes in ZiZiphus jujuba garden using water stable isotopes
1
作者 ZHONG Xiaofei ZHANG Mingjun +3 位作者 CHE Cunwei LIU Zechen LI Beibei ZHANG Yuanyuan 《Journal of Mountain Science》 SCIE CSCD 2024年第10期3263-3274,共12页
ZiZiphus jujuba,which is native to China,has become one of the main crops widely planted in the western Loess Plateau because of its drought and flood-tolerance,adaptability,and higher nutritional value of the fruit.T... ZiZiphus jujuba,which is native to China,has become one of the main crops widely planted in the western Loess Plateau because of its drought and flood-tolerance,adaptability,and higher nutritional value of the fruit.The irrigation water infiltration in Z.jujuba gardens is complex,and understanding its mechanisms is essential for efficient water use and sustainable agriculture.This knowledge helps ensure the long-term success of jujuba cultivation.This paper describes a field experiment that investigates the infiltration process of irrigation water from Z.jujuba garden and quantifies the contribution of irrigation water to soil water at different depths using the MixSIAR model.According to the FC(Field water holding Capacity)of Z.jujuba,irrigation experiments with three volumes of 80%FC,60%FC,and 40%FC are set up in this study.The study finds that water retention is better in Z.jujuba garden soils with a higher proportion of coarse gravel in the soil particle composition.Soil water content exhibits a gradient change after irrigation,with deeper wetting front transport depth observed with increased irrigation water.Additionally,there is correlation between soil temperature and soil water content.The soil water in Z.jujuba garden generally exhibits a preferential flow signal in the 0-40 cm range.Below 40 cm,a piston flow pattern dominates.The rate of soil water infiltration increases with the amount of irrigation water.In the 0-40 cm range of the soil vertical profile,irrigation water was the main contributor to soil water.Z.jujuba demonstrated flexibility in water uptake,primarily absorbing soil water at depths of 0-40 cm.For optimal growth of Z.jujuba at this stage,40%FC irrigation is recommended.The results are expected to be valuable future irrigation practices and land use planning for Z.jujuba garden in arid zones,supporting sustainable agricultural development and water management. 展开更多
关键词 Water stable isotopes Different irrigation volumes ZiZiphus jujuba Irrigation water infiltration process MixSIAR model
下载PDF
A Hybrid Attention-Based Residual Unet for Semantic Segmentation of Brain Tumor
2
作者 Wajiha Rahim Khan Tahir Mustafa Madni +5 位作者 Uzair Iqbal Janjua Umer Javed Muhammad Attique Khan Majed Alhaisoni Usman Tariq Jae-Hyuk Cha 《Computers, Materials & Continua》 SCIE EI 2023年第7期647-664,共18页
Segmenting brain tumors in Magnetic Resonance Imaging(MRI)volumes is challenging due to their diffuse and irregular shapes.Recently,2D and 3D deep neural networks have become famous for medical image segmentation beca... Segmenting brain tumors in Magnetic Resonance Imaging(MRI)volumes is challenging due to their diffuse and irregular shapes.Recently,2D and 3D deep neural networks have become famous for medical image segmentation because of the availability of labelled datasets.However,3D networks can be computationally expensive and require significant training resources.This research proposes a 3D deep learning model for brain tumor segmentation that uses lightweight feature extraction modules to improve performance without compromising contextual information or accuracy.The proposed model,called Hybrid Attention-Based Residual Unet(HA-RUnet),is based on the Unet architecture and utilizes residual blocks to extract low-and high-level features from MRI volumes.Attention and Squeeze-Excitation(SE)modules are also integrated at different levels to learn attention-aware features adaptively within local and global receptive fields.The proposed model was trained on the BraTS-2020 dataset and achieved a dice score of 0.867,0.813,and 0.787,as well as a sensitivity of 0.93,0.88,and 0.83 for Whole Tumor,Tumor Core,and Enhancing Tumor,on test dataset respectively.Experimental results show that the proposed HA-RUnet model outperforms the ResUnet and AResUnet base models while having a smaller number of parameters than other state-of-the-art models.Overall,the proposed HA-RUnet model can improve brain tumor segmentation accuracy and facilitate appropriate diagnosis and treatment planning for medical practitioners. 展开更多
关键词 MRI volumes residual Unet BraTs-2020 squeeze-excitation(SE)
下载PDF
Quinpi:Integrating Conservation Laws with CWENO Implicit Methods
3
作者 G.Puppo M.Semplice G.Visconti 《Communications on Applied Mathematics and Computation》 2023年第1期343-369,共27页
Many interesting applications of hyperbolic systems of equations are stiff,and require the time step to satisfy restrictive stability conditions.One way to avoid small time steps is to use implicit time integration.Im... Many interesting applications of hyperbolic systems of equations are stiff,and require the time step to satisfy restrictive stability conditions.One way to avoid small time steps is to use implicit time integration.Implicit integration is quite straightforward for first-order schemes.High order schemes instead also need to control spurious oscillations,which requires limiting in space and time also in the linear case.We propose a framework to simplify considerably the application of high order non-oscillatory schemes through the introduction of a low order implicit predictor,which is used both to set up the nonlinear weights of a standard high order space reconstruction,and to achieve limiting in time.In this preliminary work,we concentrate on the case of a third-order scheme,based on diagonally implicit Runge Kutta(DIRK)integration in time and central weighted essentially non-oscillatory(CWENO)reconstruction in space.The numerical tests involve linear and nonlinear scalar conservation laws. 展开更多
关键词 Implicit schemes Essentially non-oscillatory schemes Finite volumes WENO and CWENO reconstructions
下载PDF
Evaluation of 3D-CRT and VMAT Radiotherapy Plans for Left Breast Cancer with Regional Lymph Nodes Irradiation
4
作者 Houda Benmessaoud Hasnae Bouhia +4 位作者 Halima Ahmut Sanaa El Majjaoui Hanane El Kacemi Khalid Hassouni Tayeb Kebdani 《Journal of Cancer Therapy》 2023年第8期345-352,共15页
Introduction: Radiation therapy after breast surgery is an integral part of the treatment of early breast cancer. The goal of radiation therapy is to achieve the best possible coverage of the planning target volume (P... Introduction: Radiation therapy after breast surgery is an integral part of the treatment of early breast cancer. The goal of radiation therapy is to achieve the best possible coverage of the planning target volume (PTV), while reducing the dose to organs at risk (OARs) which are normal tissues whose sensitivity to irradiation could cause damage that can lead to modification of the treatment plan. In the last decade, radiation oncologist started to use the Intensity Modulated Radiotherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) for irradiating the breast, in order to achieve better dose distribution and target dose to the PTV and OAR. The aim of this study is to compare 2 external radiotherapy techniques (VMAT vs 3D) for patients with node-positive left breast cancer. Patients and Methods: We randomly selected 10 cases of postoperative radiotherapy for breast cancer in our hospital. The patients are all female, the average age was 45.4 years old, and the primary lesions are left breast. The ANOVA test was used to compare the mean difference between subgroups, and the p value Results: Dose volume histogram (DVH) was used to analyze each evaluation dose of clinical target volume (CTV) and organs at risk (OARs). Compared to 3DCRT plans, VMAT provided more uniform coverage to the breast and regional lymph nodes. The max point dose for tVMAT was lower on average (106.4% for VMAT versus 109% for 3DCRT). OAR sparing was improved with tVMAT, with a lower average V17Gy for the left lung (27.91% for VMAT versus 30.04% for 3DCRT, p and lower for V28Gy (13.75% for VMAT versus 22.34% for 3DCRT, p = 0.01). We also found a lower V35Gy for the heart on VMAT plan (p = 0.02). On the contrary, dose of contralateral breast was lower in 3DCRT than VMAT (0.59 Gy vs 3.65 Gy, p = 0.00). Conclusion: The both types of plans can meet the clinical dosimetry demands of postoperative radiotherapy for left breast cancer. The VMAT plan has a better conformity, but 3CDRT can provide a lower dose to the contralateral organs (breast and lung) to avoid the risk of secondary cancers. 展开更多
关键词 Volumetric-Modulated arc Therapy 3D-Conformal Radiation Therapy Left Breast Cancer Target Volumes Treatment Plan
下载PDF
Shrinkage and Expansive Strain of Concrete with Fly Ash and Expansive Agent 被引量:15
5
作者 高培伟 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2009年第1期150-153,共4页
The effects of fly ash and MgO-type expansive agent on the shrinkage and expan-sive strain of concrete with high magnesia cement were investigated. The results show that high volumes of fly ash may reduce the shrinkag... The effects of fly ash and MgO-type expansive agent on the shrinkage and expan-sive strain of concrete with high magnesia cement were investigated. The results show that high volumes of fly ash may reduce the shrinkage strain of concrete and inhibit the expansive strain of concrete with MgO-type expansive agent, but can not eliminate the shrinkage of concrete. MgO-type expansive agent may produce expansive strain and compensate the shrinkage strain of concrete, re-lieve the cracking risk, but the hydration product of magnesia tends to get together in paste and pro-duce expansive cracking of concrete with high magnesia content according to SEM observation. 展开更多
关键词 high volumes of fly ash MgO-bearing expansive agent high magnesia cement volume stability
下载PDF
SOME INEQUALITIES ABOUT DUAL MIXED VOLUMES OF STAR BODIES 被引量:5
6
作者 李小燕 冷岗松 《Acta Mathematica Scientia》 SCIE CSCD 2005年第3期505-510,共6页
The authors establish some inequalities about the dual mixed volumes of star bodies in Rn. These inequalities are the analogue in the Brunn-Minkowski theory of the inequalities of Marcus-Lopes and Bergstrom about symm... The authors establish some inequalities about the dual mixed volumes of star bodies in Rn. These inequalities are the analogue in the Brunn-Minkowski theory of the inequalities of Marcus-Lopes and Bergstrom about symmetric functions of positive reals. 展开更多
关键词 Brunn-Minkowski theory star bodies dual mixed volumes Aleksandrov Fenchel inequality.
下载PDF
Volume of unit ball in an n-dimensional normed space and its asymptotic properties 被引量:3
7
作者 黄智悦 何斌吾 《Journal of Shanghai University(English Edition)》 CAS 2008年第2期107-109,共3页
Let Bp^n={x∈R^b|‖x‖p≤1} be the unit ball of p norm in the n-dimensional normed space εp&n.The formula for the volume of Bp^n was obtained and its asymptotic properties were found out as n→∞and p→∞.
关键词 unit ball normed space VOLUMES gamma function asymptotic properties.
下载PDF
Voxel-based magnetic resonance imaging investigation of poor and preserved clinical insight in people with schizophrenia 被引量:3
8
作者 Adegboyega Sapara Dominic H Ffytche +2 位作者 Michael A Cooke Steven CR Williams Veena Kumari 《World Journal of Psychiatry》 SCIE 2016年第3期311-321,共11页
AIM To define regional grey-matter abnormalities in schizophrenia patients with poor insight(Insight-),relative to patients with preserved clinical insight(Insight+),and healthy controls.METHODS Forty stable schizophr... AIM To define regional grey-matter abnormalities in schizophrenia patients with poor insight(Insight-),relative to patients with preserved clinical insight(Insight+),and healthy controls.METHODS Forty stable schizophrenia outpatients(20 Insight-and 20 Insight+) and 20 healthy controls underwent whole brain magnetic resonance imaging(MRI).Insight in all patients was assessed using the Birchwood Insight Scale(BIS;a self-report measure).The two patient groups were preselected to match on most clinical and demographic parameters but,by design,they had markedly distinct BIS scores.Voxel-based morphometry employed in SPM8 was used to examine group differences in grey matter volumes across the whole brain.RESULTS The three participant groups were comparable in age [F(2,57) = 0.34,P = 0.71] and the patient groups did not differ in age at illness onset [t(38) = 0.87,P = 0.39].Insight-and Insight+ patient groups also did not differ in symptoms on the Positive and Negative Syndromes scale(PANSS):Positive symptoms [t(38) = 0.58,P = 0.57],negative symptoms [t(38) = 0.61,P = 0.55],general psychopathology [t(38) = 1.30,P = 0.20] and total PANSS scores [t(38) = 0.21,P = 0.84].The two patient groups,as expected,varied significantly in the level of BIS-assessed insight [t(38) = 12.11,P < 0.001].MRI results revealed lower fronto-temporal,parahippocampal,occipital and cerebellar grey matter volumes in Insightpatients,relative to Insight+ patients and healthy controls(for all clusters,family-wise error corrected P < 0.05).Insight+ patient and healthy controls did not differ significantly(P > 0.20) from each other.CONCLUSION Our findings demonstrate a clear association between poor clinical insight and smaller fronto-temporal,occipital and cerebellar grey matter volumes in stable long-term schizophrenia patients. 展开更多
关键词 PSYCHOSIS INSIGHT Grey matter VOLUMES Fronto-temporal Neural networks Birchwood INSIGHT scale
下载PDF
Lower-Dimensional Volumes and Kastler-Kalau-Walze Type Theorem for Manifolds with Boundary 被引量:3
9
作者 王勇 《Communications in Theoretical Physics》 SCIE CAS CSCD 2010年第7期38-42,共5页
In this paper,we define lower-dimensional volumes of spin manifolds with boundary.We compute thelower-dimensional volume Vol^((2,2)) for 5-dimensional and 6-dimensional spin manifolds with boundary and we also getthe ... In this paper,we define lower-dimensional volumes of spin manifolds with boundary.We compute thelower-dimensional volume Vol^((2,2)) for 5-dimensional and 6-dimensional spin manifolds with boundary and we also getthe Kastler-Kalau-Walze type theorem in this case. 展开更多
关键词 lower-dimensional volumes noncommutative residue for manifolds with boundary gravitationalaction for manifolds with boundary
下载PDF
Application of prolonging small feeding volumes early in life to prevent of necrotizing enterocolitis in very low birth weight preterm infants 被引量:3
10
作者 Qiu-fang Li Hua Wang +2 位作者 Dan Liu Yi Tang Xin-fen Xu 《International Journal of Nursing Sciences》 2016年第1期45-49,共5页
Objective:To study the effects of prolonging small feeding volumes early in life on the incidence of necrotizing enterocolitis(NEC)in very low birth weight(VLBW)preterm infants.Methods:A total of 128 VLBW infants who ... Objective:To study the effects of prolonging small feeding volumes early in life on the incidence of necrotizing enterocolitis(NEC)in very low birth weight(VLBW)preterm infants.Methods:A total of 128 VLBW infants who could not be breastfed were assigned into the experimental group(63 cases)and the control group(65 cases)using a random number table.The experiment group was fed 12 mL/(kg·d)on day 1 which was increased to 24 mL/(kg·d)for the first 10 study days.The control group was fed 12 mL/(kg·d)for the first 14e48 hours.Then,the feeding volume increased by 24-36 mL/(kg·d)up to 140e160 mL/(kg·d)and maintained until the 10th day after birth.The incidence of feeding intolerance and NEC,duration of hospitalization,time to full enteral feedings,incidence of intrahepatic cholestasis,and the levels of gastrin and motilin in serum were assessed.Results:The incidence of feeding intolerance was significantly lower in the experimental group compared with the control group(15.87% vs.33.84%).There was a significant reduction in the incidence of NEC between the experimental and control groups(7.9% vs.16% in the control group).Conclusion:A protocol that prolongs small feeding volumes early in life can reduce the incidence and severity of NEC,but still warrants further study. 展开更多
关键词 Infant formula Necrotizing enterocolitis Preterm infant Prolonging small feeding volumes Very low birth weight infant
下载PDF
Cardiac remodeling as a consequence of atrial fibrillation: An anatomical study of perfusion-fixed human heart specimens 被引量:1
11
作者 Christopher D Rolfes Stephen A Howard +1 位作者 Ryan P Golf Paul A Iaizzo 《Journal of Geriatric Cardiology》 SCIE CAS CSCD 2011年第3期141-146,共6页
Background Atrial fibrillation (AF) causes a continuum of atrial anatomical remodeling. Methods Using a library of perfusion-fixed human hearts, specimens with AF were compared to controls. During this preliminary a... Background Atrial fibrillation (AF) causes a continuum of atrial anatomical remodeling. Methods Using a library of perfusion-fixed human hearts, specimens with AF were compared to controls. During this preliminary assessment study, direct measurements were taken of atrial volume, pulmonary vein (PV) circumference, and left atrial (LA) wall thicknesses. Results Hearts with AF typically had larger atrial volumes, as well as a much larger variation in volume compared to controls (range of 59.6-227.1 mL in AF hearts compared to 65.1-115.9 mL in controls). For all hearts, right PVs were larger than left PVs (mean: 171.4 ± 84.6 mm^2 for right and 1182 ± 50.1 mm^2 for left, P 〈 0.005). LA wall thicknesses ranged from 0.7 mm to 3.1 mm for both AF and control hearts. Conclusions Hearts with AF had a large range of sizes which is consistent with the progression of atrial remodeling during AF. The large range of thicknesses will influence the amount of energy needed to create transmural lesions during ablation procedures. 展开更多
关键词 left atrial dimensions VOLUMES pulmonary vein ostia atrial fibrillation
下载PDF
Numerical Study of Natural Convection in an Inclined Porous Cavity 被引量:1
12
作者 Saad Adjal Sabiha Aklouche-Benouaguef Belkacem Zeghmati 《Fluid Dynamics & Materials Processing》 EI 2022年第5期1389-1397,共9页
Two-dimensional transient laminar natural convection in a square cavity containing a porous medium and inclined at an angle of 30°is investigated numerically.The vertical walls are differentially heated,and the h... Two-dimensional transient laminar natural convection in a square cavity containing a porous medium and inclined at an angle of 30°is investigated numerically.The vertical walls are differentially heated,and the horizontal walls are adiabatic.The effect of Rayleigh number on heat transfer and on the road to chaos is analyzed.The natural heat transfer and the Darcy Brinkman equations are solved by using a finite volume method and a Tri Diagonal Matrix Algorithm(TDMA).The results are obtained for a porosity equal to 0.45,a Darcy number and a Prandtl respectively equal to 10^(-3)and 0.71;they are analyzed in terms of streamlines,isotherms,phase portrait,attractors,and spectra amplitude as a function of the Rayleigh number.It is found that,as Rayleigh number increases,the natural convection changes from a steady state to a time-periodic state and finally to a chaotic condition. 展开更多
关键词 Natural convection porous medium finite volumes CHAOS ATTRACTORS
下载PDF
Colonoscopy procedural volume increases adenoma and polyp detection rates in gastroenterology trainees 被引量:1
13
作者 Emad Qayed Ravi Vora +1 位作者 Sara Levy Roberd M Bostick 《World Journal of Gastrointestinal Endoscopy》 CAS 2017年第11期540-551,共12页
AIM To investigate changes in polyp detection throughout fellowship training, and estimate colonoscopy volume required to achieve the adenoma detection rate(ADRs) and polyp detection rate(PDRs) of attending gastroente... AIM To investigate changes in polyp detection throughout fellowship training, and estimate colonoscopy volume required to achieve the adenoma detection rate(ADRs) and polyp detection rate(PDRs) of attending gastroenterologists.METHODS We reviewed colonoscopies from July 1, 2009 to June 30, 2014. Fellows' procedural logs were used to retrieve colonoscopy procedural volumes, and these were treated as the time variable. Findings from screening colonoscopies were used to calculate colonoscopy outcomes for each fellow for the prior 50 colonoscopies at each time point. ADR and PDR were plotted against colonoscopy procedural volumes to produce individual longitudinal graphs. Repeated measures linear mixed effects models were used to study the change of ADR and PDR with increasing procedural volume.RESULTS During the study period, 12 fellows completed full three years of training and were included in the analysis. The average ADR and PDR were, respectively, 31.5% and 41.9% for all fellows, and 28.9% and 38.2% for attendings alone. There was a statistically significant increase in ADR with increasing procedural volume(1.8%/100 colonoscopies, P = 0.002). Similarly, PDR increased 2.8%/100 colonoscopies(P = 0.0001), while there was no significant change in advanced ADR(0.04%/100 colonoscopies, P = 0.92). The ADR increase was limited to the right side of the colon, while the PDR increased in both the right and left colon. The adenoma per colon and polyp per colon also increased throughout training. Fellows reached the attendings' ADR and PDR after 265 and 292 colonoscopies, respectively.CONCLUSION We found that the ADR and PDR increase with increasing colonoscopy volume throughout fellowship. Our findings support recent recommendations of ≥ 275 colonoscopies for colonoscopy credentialing. 展开更多
关键词 Screening colonoscopy Colorectal cancer Polyp detection rate Colonoscopy volumes Adenoma detection rate Gastroenterology training
下载PDF
Is obesity related to the lung function of non-asthmatic children? 被引量:1
14
作者 Andrew Fretzayas Maria Moustaki +1 位作者 Ioanna Loukou Konstantinos Douros 《World Journal of Clinical Pediatrics》 2018年第2期67-74,共8页
Overweight and obesity are highly prevalent in developed and developing countries among children and adolescents. During the last two decades, it became evident that excess weight is adversely related to respiratory h... Overweight and obesity are highly prevalent in developed and developing countries among children and adolescents. During the last two decades, it became evident that excess weight is adversely related to respiratory health in childhood and adolescence mainly in terms of asthma occurrence. Additionally, there is a mounting body of evidence that overweight/obesity may also affect lung function in non-asthmatic subjects. The aim of this review was to present and discuss the studies that investigated this issue in non-asthmatic children and adolescents. Only a few studies have evaluated the impact of excess weight on static volumes and their results point towards an inverse relationship between overweight/obesity and functional residual capacity. More studies have been conducted on the impact of excess weight on dynamic lung volumes with inconsistent, however, results. Nevertheless, a relatively consistent finding was that the ratio of forced expiratory volume in 1 s/forced vital capacity was significantly lower among overweight/obese children compared to their counterparts with normal weight. The underlying mechanisms of these observations have not been adequately elucidated but it is believed to result from complex interaction of mechanical, developmental, and metabolic causes. There is a need for more welldesigned studies in order to clarify the impact of excess weight on lung function in non-asthmatic subjects, as well as to explore the contribution of factors such as duration and degree of obesity, and fat distribution. Despite the absence of conclusive data, there are stillconvincing evidence to be communicated to the children and their families as part of the arguments to encourage them to adopt a healthier lifestyle. 展开更多
关键词 OBESITY LUNG FUNCTION SPIROMETRY LUNG VOLUMES PLETHYSMOGRAPHY
下载PDF
Calculations of Heat Transfer in Torch Furnaces by Gas Volume Radiation Laws 被引量:1
15
作者 A. N. Makarov 《World Journal of Engineering and Technology》 2016年第3期488-503,共17页
The results stemming from the calculation of heat transfer in torch furnaces by the laws, relating to radiation from solid surfaces and gas volumes are analyzed. The article presents the laws for radiation from gas vo... The results stemming from the calculation of heat transfer in torch furnaces by the laws, relating to radiation from solid surfaces and gas volumes are analyzed. The article presents the laws for radiation from gas volumes and the procedure for calculating heat transfer in torch furnaces, fire boxes, and combustion chambers, elaborated on their basis. The example of heat transfer calculation in a torch furnace is given, and it is significantly non-uniform in nature. Non-uniformity of heat flux distribution on heating surfaces is given. According to the results of calculations, a new furnace is designed to decrease the non-uniformity of ingot heating, fuel rate, and increase the furnace capacity. The calculation results of the distribution of heat fluxes on the heating surfaces are given in changing torch geometric dimensions. These results are confirmed by experimental studies. 展开更多
关键词 Heat Transfer Gas Volumes Heat Radiation Laws TORCH FURNACE
下载PDF
Thermodynamic Fit Functions of the Two-Phase Fluid and Critical Exponents 被引量:1
16
作者 Albrecht Elsner 《Engineering(科研)》 2014年第12期789-826,共38页
Two-phase fluid properties such as entropy, internal energy, and heat capacity are given by thermodynamically defined fit functions. Each fit function is expressed as a temperature function in terms of a power series ... Two-phase fluid properties such as entropy, internal energy, and heat capacity are given by thermodynamically defined fit functions. Each fit function is expressed as a temperature function in terms of a power series expansion about the critical point. The leading term with the critical exponent dominates the temperature variation between the critical and triple points. With β being introduced as the critical exponent for the difference between liquid and vapor densities, it is shown that the critical exponent of each fit function depends (if at all) on β. In particular, the critical exponent of the reciprocal heat capacity c﹣1 is α=1-2β and those of the entropy s and internal energy u are?2β, while that of the reciprocal isothermal compressibility?κ﹣1T is γ=1. It is thus found that in the case of the two-phase fluid the Rushbrooke equation conjectured α +?2β + γ=2 combines the scaling laws resulting from the two relations c=du/dT and?κT=dlnρ/dp. In the context with c, the second temperature derivatives of the chemical potential μ and vapor pressure p are investigated. As the critical point is approached, ﹣d2μ/dT2 diverges as c, while?d2p/dT2 converges to a finite limit. This is explicitly pointed out for the two-phase fluid, water (with β=0.3155). The positive and almost vanishing internal energy of the one-phase fluid at temperatures above and close to the critical point causes conditions for large long-wavelength density fluctuations, which are observed as critical opalescence. For negative values of the internal energy, i.e. the two-phase fluid below the critical point, there are only microscopic density fluctuations. Similar critical phenomena occur when cooling a dilute gas to its Bose-Einstein condensate. 展开更多
关键词 CRITICAL Condition U = 0 CRITICAL OPALESCENCE Rushbrooke Equation THERMODYNAMIC FIT FUNCTIONS for Saturated Water Vapor and Liquid Volumes Vapor Pressure Chemical Potential Entropy Internal ENERGY Free ENERGY Heat Capacity
下载PDF
Volume, Side-Area, and Force Direction of Berkovich and Cubecorner Indenters, Novel Important Insights 被引量:1
17
作者 Gerd Kaupp 《Advances in Materials Physics and Chemistry》 2021年第11期212-241,共30页
The iteration-free physical description of pyramidal indentations with closed mathematical equations is comprehensively described and extended for creating new insights in this important field of research and app... The iteration-free physical description of pyramidal indentations with closed mathematical equations is comprehensively described and extended for creating new insights in this important field of research and applications. All calculations are easily repeatable and should be programmed by instrument builders for even easier general use. Formulas for the volumes and side-areas of Berkovich and cubecorner as a function of depth are deduced and provided, as are the resulting forces and force directions. All of these allow for the detailed comparison of the different indenters on the mathematical reality. The pyramidal values differ remarkably from the ones of so-called “equivalent cones”. The worldwide use of such pseudo-cones is in severe error. The earlier claimed and used 3 times higher displaced volume with cube corner than with Berkovich is disproved. Both displace the same amount at the same applied force. The unprecedented mathematical results are experimentally confirmed for the physical indentation hardness and for the sharp-onset phase-transi</span></span><span style="white-space:normal;"><span style="font-family:"">- </span></span><span style="white-space:normal;"><span style="font-family:"">tions with calculated transition energy. The comparison of both indenters pro</span></span><span style="white-space:normal;"><span style="font-family:"">vides novel basic insights. Isotropic materials exhibit the same phase transition onset force, but the transition energy is larger with the cube corner, due to higher force and flatter force direction. This qualifies the cube</span></span><span style="white-space:normal;"><span style="font-family:""> </span></span><span style="white-space:normal;"><span style="font-family:"">corner for fracture toughness studies. Pile-up is not from the claimed “friction with the indenter”. Anisotropic materials with cleavage planes and channels undergo sliding along these</span></span><span style="white-space:normal;"><span style="font-family:""> under pressure</span></span><span style="white-space:normal;"><span style="font-family:"">, both to the surface and internally. Their volumes add to the depression volume. These volumes are essential for the exemplified pile-up management. Phase-transitions produce polymorph interfaces that are nucleation sites for cracks. Technical materials must be developed with onset forces higher than the highest thinkable stresses (at airliners, bridges</span></span><span style="white-space:normal;"><span style="font-family:"">,</span></span><span style="white-space:normal;"><span style="font-family:""> etc</span></span><span style="white-space:normal;"><span style="font-family:"">.</span></span><span style="white-space:normal;"><span style="font-family:"">). This requires urgent revision of ISO 14577-ASTM stan</span></span><span style="white-space:normal;"><span style="font-family:"">dards. 展开更多
关键词 Closed Mathematical Formulas Force Direction Indenter Volumes and Side-Areas Iteration-less Calculations Equal Base-Area Cones PILE-UP Phase-Transition-Onset and -Energy
下载PDF
Densities and excess molar volumes of mixtures containing diesel,biodiesel and alkanols at temperatures from 288.15 to 313.15 K
18
作者 Sunita Malik Poonam Jangra Darolia +1 位作者 S.K.Garg V.K.Sharma 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2021年第6期198-207,共10页
The present work is focusing on the synthesization and physico-chemical properties of Jatropha curcas biodiesel with diesel and alcohols.The densities of binary diesel(2)+1-alkanols(C_(3) or C_(4))(3)and ternary Jatro... The present work is focusing on the synthesization and physico-chemical properties of Jatropha curcas biodiesel with diesel and alcohols.The densities of binary diesel(2)+1-alkanols(C_(3) or C_(4))(3)and ternary Jatropha curcas biodiesel(1)+diesel(2)+1-alkanols(C_(3)or C_(4))(3)blends have been reported over full range of composition at temperatures within range 288.15 to 313.15 K.Also densities of Jatropha curcas biodiesel(1)+diesel or 1-alkanols(C_(3) or C_(4))(2)blends have been measured at 313.15 K.Excess molar volumes,V^E,V^E_(123)of binary and ternary blends were calculated from the measured data and the derived properties were correlated to composition using Redlich-Kister equation.A reasonable agreement was found between the measured and estimated values.Further,densities and excess molar volumes data were reasoned to discuss molecular interactions taking into consideration effect of composition and temperature. 展开更多
关键词 Jatropha curcas biodiesel DIESEL ALCOHOLS Blends Density Excess molar volumes
下载PDF
Effects of smoking on cerebral and ventricular volumes in healthy males
19
作者 Hyun-Jun Kim Mi-Hyun Choi +9 位作者 Beob-Yi Lee Su-Jeong Lee Jae-Woong Yang Ji-Hye Kim Jin-Seung Choi Dong-Won Kang Jang-Yeon Park Jae-Hoon Jun Gye-Rae Tack Soon-Cheol Chung 《Neural Regeneration Research》 SCIE CAS CSCD 2011年第1期72-75,共4页
Previous studies have reported decreased cerebral volume as a result of smoking. However, little is known about accompanying changes in ventricular volume for healthy subjects who smoke, although ventricular volume is... Previous studies have reported decreased cerebral volume as a result of smoking. However, little is known about accompanying changes in ventricular volume for healthy subjects who smoke, although ventricular volume is increased in patients with multiple sclerosis who smoke. The present study analyzed whether cerebral volume decreased with smoking through the use of magnetic resonance imaging. In addition, accompanying changes in ventricular volume that resulted from decreased cerebral volume and smoking were analyzed in healthy subjects. When multivariate analysis of covariance was performed by integrating the 2 age groups, aged 20-28 years and 40-49 years, with statistical significance, results showed that cerebral volume of smokers was smaller and ventricular volume was greater compared with the non-smokers. These findings suggest that ventricular volume changes could be utilized to characterize the effects of smoking. 展开更多
关键词 SMOKING cerebral and ventricular volumes magnetic resonance imaging
下载PDF
Hippocampus and amygdala volumes in patients with vaginismus
20
作者 Murad Atmaca Sema Baykara +3 位作者 Omer Ozer Sevda Korkmaz Unsal Akaslan Hanefi Yildirim 《World Journal of Psychiatry》 SCIE 2016年第2期221-225,共5页
AIM: To compare hippocampus and amygdala volumes of patients with vaginismus with those of healthy control subjects.METHODS: Magnetic resonance imaging was performed on ten patients with vaginismus and ten control sub... AIM: To compare hippocampus and amygdala volumes of patients with vaginismus with those of healthy control subjects.METHODS: Magnetic resonance imaging was performed on ten patients with vaginismus and ten control subjects matched for age and gender. Volumes of the hippocampus and amygdala were blindly measured. RESULTS: We found that the mean right amygdala volume of patients with vaginismus were smaller than that of the healthy controls. With regard to hippocampus volumes, the mean left and right hippocampus volumes were smaller than those of the healthy controls. CONCLUSION: Our present findings suggest that there have been hippocampus and amygdala structural abnormalities in patients with vaginismus. These changes provide the notion that vaginismus may be a fear-related condition. 展开更多
关键词 VAGINISMUS HIPPOCAMPUS AMYGDALA VOLUMES PATIENTS
下载PDF
上一页 1 2 4 下一页 到第
使用帮助 返回顶部