Load Criteria Research Articles

Elements of thermomechanics of plasticity under complex loading

The problem of the theory of elastic-plastic process is the establishment of criteria for loading and unloading. In this paper, the equations of the process describe the transition from Euclidean metric, normal for the source deviatoric space, to internal metrics, definitely related to the processes of deformations and loadings. This transition allows without additional assumptions to introduce so-called structural parameters characterizing the irreversible behavior of the material and to build a thermomechanics variant, providing a wide range of opportunities to determine all thermodynamic parameters of the model and formulation of the thermodynamic inequalities.

Computer-aided design of gas turbine engines rotors

The technology of the optimal design when designing the structure of the rotor disc for turbomachines is showed. The features of the organization of computer-aided design of gas turbine engine rotor are considered. The calculations of gas turbine engine rotor parts optimal form were made. Structural optimization (shape optimization) was applied to optimal design of compressor disk depending on various factors of loading and optimization criteria.

Antinuclear Antibody Positivity in Chronic Hepatitis C Patients: Effect on Histopathology and Impact on Early Response to Combined Antiviral Therapy

Background and study aim : The prevalence of antinuclear antibody (ANA) has been documented in patients with hepatitis C virus (HCV) infection. Hepatitis C virus infection plays an important role in the pathogenesis of immunological derangement, but the mechanism remains unclear. The aim of this study is to detect the significance of ANA positivity and its impact on histopathology and early virological response (EVR) to combined antiviral therapy in chronic HCV patients. . Patients and Methods:Two hundred Egyptian chronic HCV naive patients were enrolled in this study. Antinuclear antibody (ANA) was detected by ELISA and it was considered positive with a titer > 1 : 14 by indirect immunofluorescence. Complete laboratory investigations and histological examination were done as a pretreatment work up for all patients. Patients were followed up during treatment and EVR was assessed in ANA positive and negative patients. Results: There was a statistically significant difference between ANA positive and negative patients regarding viral load and histopathological criteria and no significant difference was detected regarding other demographic and laboratory criteria. EVR was close in ANA positive and ANA negative patients (77 for the former Vs. 80 for the later with P = 0.33). No autoimmune manifestations were detected during treatment among positive cases. Except for ALT & AST levels no statistically significant differences were detected between ANA positive and negative cases regarding haematological data, thyroid dysfunction. BMI, ALT levels, viral load and fibrosis stages were independent predictors of EVR. Conclusion: ANA postivity in chronic HCV patients was associated with advanced fibrosis but didn't affect treatment response.

원주방향 표면 결함이 존재하는 배관에 가해지는 비틀림을 포함한 복합하중에 대한 한계하중식 제시

Since the Fukushima nuclear accident, several researchers are extensively studying the effect of torsion on the piping systems In nuclear power plants. Piping installations in power plants with a circumferential crack can be operated under combined loading conditions such as bending and torsion. ASME Code provides flaw evaluations for fully plastic fractures using limit load criteria for the structural integrity of the cracked pipes. According to the recent version of Code, combined loadings are provided only for the membrane and bending. Even though actual operating conditions have torsion loading, the methodology for evaluating torsion load is not established. This paper provides the results of limit load analyses by using finite element models for circumferentially cracked pipes under pure bending, pure torsion, and combined bending and torsion with tension. Theoretical limit load solutions based on net-section fully plastic criteria are suggested and verified with the results of finite element analyses.

A pilot study on quantification of training load: The use of HRV in training practice

Recent laboratory studies have suggested that heart rate variability (HRV) may be an appropriate criterion for training load (TL) quantification. The aim of this study was to validate a novel HRV index that may be used to assess TL in field conditions. Eleven well-trained long-distance male runners performed four exercises of different duration and intensity. TL was evaluated using Foster and Banister methods. In addition, HRV measurements were performed 5 minutes before exercise and 5 and 30 minutes after exercise. We calculated HRV index (TLHRV) based on the ratio between HRV decrease during exercise and HRV increase during recovery. HRV decrease during exercise was strongly correlated with exercise intensity (R = −0.70; p < 0.01) but not with exercise duration or training volume. TLHRV index was correlated with Foster (R = 0.61; p = 0.01) and Banister (R = 0.57; p = 0.01) methods. This study confirms that HRV changes during exercise and recovery phase are affected by both intensity and physiological impact of the exercise. Since the TLHRV formula takes into account the disturbance and the return to homeostatic balance induced by exercise, this new method provides an objective and rational TL index. However, some simplification of the protocol measurement could be envisaged for field use.

On specific features of modeling electromagnetic field in the connection area of side busbar packages to graphitization furnace current leads

This paper describes methods for intensification of the electrical parameters and calculation of the effective cross sections of the end busbars, the current leads of the graphitization furnaces, and the sections of the side busbar packages on the side of an ac graphitization furnace rear end, as well as increasing the energy efficiency of both the furnace equipment and the graphitization electrical system as a whole developed to produce marketable and competitive products. The existing models and calculation methods are inadequate, significantly distort the actual picture of the electromagnetic processes in a complex spatial system of the current leads in a graphitization furnace and the busbar packages of the furnace loop, and do not meet current accuracy standards. In this work, conjugate three-dimensional electromagnetic and thermal fields in the connection area of the side busbar packages to the current leads of an ac graphitization furnace have been numerically simulated by finite element methods and on the basis of the theories of electromagnetic fields and of heat and mass transfer. This paper presents theoretical studies and a simulation of the electromagnetic, electrothermal, and heat-and-mass transfer processes in the connection areas of the side busbar packages to the current leads of the graphitization furnace based on numerical implementation by a finite element method of a generalized 3D model of dc and ac graphitization that considers the temperature dependences of the electrophysical and thermophysical properties of the materials of the busbars and the current leads. A technique for calculation of the effective cross sections of the end busbars according to the equal load criteria has been proposed, which ensures reductions in the weight and the electrical losses in the end busbars. The pattern and regularities of distribution of the current densities and the specific electric losses in the end busbar packages and the current leads of the ac graphitization furnaces have been defined. It has been established that selection of effective cross sections of the end busbar packages based on the criteria of equal loads in terms of the current density and the specific electric losses enables a reduction in the weight by 12% and in the active losses by 15% as compared to the default design, thus enhancing the energy efficiency of the graphitization electrical system. The proposed technique can be applied to both direct action resistance furnaces and high-capacity electric arc furnaces of ac power frequency.

Optimizing fish sampling for fish–mercury bioaccumulation factors

Fish Bioaccumulation Factors (BAFs; ratios of mercury (Hg) in fish (Hgfish) and water (Hgwater)) are used to develop total maximum daily load and water quality criteria for Hg-impaired waters. Both applications require representative Hgfish estimates and, thus, are sensitive to sampling and data-treatment methods. Data collected by fixed protocol from 11 streams in 5 states distributed across the US were used to assess the effects of Hgfish normalization/standardization methods and fish-sample numbers on BAF estimates. Fish length, followed by weight, was most correlated to adult top-predator Hgfish. Site-specific BAFs based on length-normalized and standardized Hgfish estimates demonstrated up to 50% less variability than those based on non-normalized Hgfish. Permutation analysis indicated that length-normalized and standardized Hgfish estimates based on at least 8 trout or 5 bass resulted in mean Hgfish coefficients of variation less than 20%. These results are intended to support regulatory mercury monitoring and load-reduction program improvements.

G0301101 き裂進展を考慮したスポット溶接部の疲労寿命解析(第1報,スポット溶接部の疲労き裂アスペクト比の計測)

Although resistance spot welded joints are widely applied for fabrication of the monocoque body of cars, fatigue strength of the joints are less than the base materials in general. It is very important for satisfying the structural integrities of car bodies to evaluate the fatigue performance of spot welded joints. On the other hand, the S-N curves approach for the fatigue life prediction, which is commonly applied in the structural design stages, cannot give the fatigue crack growth history. Therefore, the fracture mechanics approach for estimating the fatigue crack growth history is expected. Improved effective stress intensity factor range based on the RPG load criterion and the numerical simulation method of fatigue crack growth which consider the fatigue crack opening and closing behaviour of the crack proposed by authors' group can be powerful method to estimate fatigue crack growth history under arbitrary loading sequences. This procedure could be applied not only a through thickness crack but also surface cracks from a sound stress concentration part. However, the changing manner of aspect ratio of a surface crack, which corresponds to the relationship between the aspect ratio and the dimensionless crack depth, must be given in advance. The aspect ratios of a fatigue surface crack occurred at the spot welded toe in SPCC270, SPCD270 and SPC440 steels, which are commonly applied for car bodies, during the growth were measured and confirmed the characteristics of behaviour of the aspect ratio for spot welded joints.

MATERIAL CONSUMPTION CRITERIA OF PISTON – CON – ROD ELEMENTS SYSTEM OF COMBUSTION ENGINE

The following article includes the analysis of mechanical and thermal load criteria of combustion engine. Those criteria have been divided into tribological, technical in detail and technical in general. The above criteria have been related to piston-con-rod system, in which, two tribological centres were specified. One centre included, piston-piston rings and cylinder, in which, piston rings serve as labyrinth seal and the cylinder constitutes piston guides. Crank bearings and main bearings of engine crankshaft constitute the second centre. From the point of tribological view, piston-piston rings and cylinder constitute slide and thrust bearing lubricated hydrodynamically, while crankshaft bearings a-c-t as slide and journal bearings also lubricated hydrodynamically. In the description of thermal load of the above-mentioned tribological centres, special attention was paid to criteria that ensure their motion reliability and durability of engine operation. Whereas in the description of mechanical load of elements constituting investigated centres, some criteria were determined resulting from their functionality and fatigue strength of the material they were made of. Criteria of thermal loads were based on mean density flux of heat conducted through the walls of engine elements, paying attention to their low precision of evaluation. It has been emphasized that synthetic criteria indicators are the most precise. They are determined on the basis of engine load measurements during its operation. Those criteria allow us to describe the operating process of con-rod-piston diesel engines and at the same time it is possible to expose their technical condition which is of essential practical meaning. The wear process of tribological centres that takes place during operating in piston-con-rod system, affects the course of engine working process and its techno-economic indicators.

Comparative Analysis of Sino-Foreign Wind Load Standard

It has great significanceto conduct comparative analysis on wind load criteria at home and abroad forimproving anti-wind load capacity of the structure. A brief overview of Chinese,American, European and Australia wind load design codes of structure ispresented in this paper. The difference among these wind load codes, theadvantages and disadvantages of Chinese related standards are pointed out.Through comparison of wind load standard between Chinese code and otherstandards, through learning from foreign experience about the determination ofwind load criteria, improvement of wind load of electrical equipment andstandard revised recommendations are provided.

Towards a Conceptual Sustainable Packaging Development Model: A Corrugated Box Case Study

Corrugated package designers are focused on balancing the need for product protection, material use efficiency and the packaging material's impact on the environment in the supply chain. The purpose of this paper is to develop a conceptual sustainable packaging model that integrates the variables of technical design, supply chain systems and environmental factors and then use the model to identify to improve upon corrugated container design. A model was developed, from the extant literature, and a case study was performed on a corrugated container. This is believed to be a unique integrated model of most relevant agents related to the design and implementation of a corrugated box through a supply chain from design to potential post-consumer reuse. From this study, we found opportunities to improve the environmental design of the corrugated container through four ex ante design stages, and two ex post facto supply chain stages. Further, research can evaluate and refine this model via a ‘live supply chain’ for use in guiding corrugated box material selection design and reuse/recycling. Integration of the design criterion for a unit load in the supply chain creates opportunity to observe the packaging system holistically. Waste in the manufacturing process and CO2 emissions are traced along the material flow until the end of its useful life to provide an overall picture of the packaging system. Copyright © 2014 John Wiley & Sons, Ltd.

WIND TUNNEL TEST FOR CALCULATING WIND FORCES ON SCAFFOLDS WITH BASEBOARD HEIGHT AS A PARAMETER

The Japanese Industrial Safety and Health Law was revised in March 2009 to introduce new measures concerning accidental falls in the construction industry. This revision mandates the use of guard rails, handrails, and other scaffold components. The wind load criteria and structural specifications of scaffolds are regulated by current design codes. Nevertheless, these provisions do not necessarily comply with the newly incorporated legal requirements because they apply to old-style scaffolds. This study examined the wind force on scaffolds by wind tunnel test, with baseboard height used as a parameter. The wind force coefficient of one story of scaffolds was calculated. Wind force coefficient increased as baseboard height increased. The wind force on the scaffolds equipped with baseboards is 9.2 times that on the scaffolds without baseboards. The baseboard must be greater than or equal to 15 cm to satisfy regulation requirements. The wind force coefficient of scaffolds with a 15 cm baseboard is 1.5 times that of the scaffolds without a baseboard. In scaffold design, baseboard height should be considered to guarantee a suitable wind force coefficient.

Mechanical Performance of RC and SFRC Precast Tunnel Lining Segments: A Case Study

Tunnels play a key role in facilitating the movement of people, goods, and services. The functionality of tunnels depends on the structural and durability performance of its lining system. Tunnel lining systems act as lines of defense against large overburden loads and complex geotechnical surrounding conditions. In this study, the structural behavior of precast concrete tunnel lining (PCTL) segments from a subway extension tunnel project in Canada was investigated. Flexural monotonic and cyclic load tests were performed on full-scale conventional reinforced concrete (RC) and steel fiber-reinforced concrete (SFRC) PCTL segments to evaluate their bending resistance. Moreover, a thrust load test was conducted to simulate the thrust loading action during tunnel boring machine operation. As expected, flexural test results indicate that the peak load-carrying capacity of RC segments was higher than that of the SFRC segments. However, SFRC segments exhibited higher cracking load and more stable post-peak cracking behavior compared to that of RC segments. RC and SFRC segments exhibited similar behavior during thrust load tests. Both types of segments satisfied the design flexural capacity and thrust loading criteria for monotonic and cyclic loads. The SFRC crack control capability supports its potential as an alternative for conventional RC tunneling segments.

Invariance in non-isothermal generalized plasticity

Theoretical issues related to the covariant structure of non-isothermal generalized plasticity in large deformations are studied in depth. For this purpose, the tensor analysis on manifolds is utilized and the manifold structure of both the ambient and the state spaces is postulated. Building on this, a covariant structure of the theory is constructed within a strain–space formulation. Thermomechanical loading criteria in both Lagrangian and Eulerian descriptions are derived in a deformation–temperature space. Based on geometrical concepts, classical non-isothermal plasticity is derived as a special case. The invariance properties of the local form of the balance of energy equation are systematically engaged for the derivation of the thermomechanical state equations. It is specifically shown that the local form of the covariant balance of energy equation does not yield the Doyle–Ericksen formula and the standard entropy–temperature constitutive relation, unless a further assumption is made. A derivation of the spatial form of the Duhamel–Neumann hypothesis on a decomposition of the rate of deformation tensor into its mechanical and thermal parts is performed as well. The covariance concept is specialized further by the construction of a material model within the context of classical metal plasticity. The proposed model is tested numerically for the solution of two problems of non-isothermal large-scale plastic flow.

Reducing air emissions from tanneries with tradable permits

Purpose – Tanneries present heavy environmental impacts due to air emissions. Specific quality objectives are fixed by European Directives concerning air and, in particular, volatile organic compounds. The purpose of this paper is to present a proposal for the management of air emissions with a view to achieve quality standards in the Italy's largest tannery district by means of a tradable emissions permits (TEPs) system. Design/methodology/approach – A methodological approach is presented and analysed. The proposed system is based on the “bubble” configuration, which appears to be an effective and feasible application based on the total maximum daily load criterion, supported by the air quality standards or the environmental risk assessment (ERA) procedure. Findings – The TEP system favours technological improvements in the reduction of emissions. The system may not provide a solution to the unpleasant odours deriving from the tanneries, but its application supported by ERA will make it possible to define the admissible levels of air pollution and improve the general state of air quality. Research limitations/implications – Although the study is not exhaustive and requires further investigation in the economic, legal, administrative and air pollution sectors, it does give the basic elements for a preliminary analysis. The evident lack of experimental data concerning weather and climatic features, intrinsic to exposure assessment, has been pointed out. Originality/value – This study proposes a methodological pathway aimed at defining the system of tradable permits by verifying the existence and availability of the necessary data. The proposed TEP system can be extended to other homogeneous industrial districts with an appropriate selection of one or more critical parameters.

Study on Wind Load about Rotary Reticulated Shell by the Wind Tunnel Experiment

This paper is to study the wind load of rotary reticulated shell by experimental methods. The article conduct rigid model experiments to reticulated shell, measure wind pressure distribution on shell’top. Similar conditions is to meet production model:geometric similarity,flow similarity , Reynolds number equal. These results can be used as a reference for the new version of the wind load criteria.

Validity of Korean Version of Functional Outcomes of Sleep Questionnaire in Patients with Simple Snoring and Obstructive Sleep Apnea

Background and ObjectiveaaWe developed a Korean version of the Functional Outcomes of Sleep Questionnaire (K-FOSQ) and investigated its reliability and validity in simple snorer or obstructive sleep apnea (OSA) patients. MethodsaaA total 432 participants (70% men, 84% OSA, mean age 50.0 ± 9.8 years) who were simple snorers or had OSA were included. We assessed the internal consistency, test-retest reliability, factor analysis, multitrait scaling analysis, and the concurrent validity of the K-FOSQ. Participants completed a battery of questionnaires including the Epworth Sleepiness Scale (ESS), Short Form-36 Health Survey (SF-36), Medical Outcomes Study-Sleep (MOS-Sleep) Scale, and Beck Depression Inventory (BDI). ResultsaaFactor analysis identified five factors, in which only 24 items met the loading criteria. The five factors of K-FOSQ accounted for 73.0% of the variance. Cronbach’s alpha coefficient for all domains exceeded the 0.70 standard for internal consistency. Test-retest re liability was acceptable (r = 0.41–0.93). Item-domain correlations ranged from 0.37 to 0.90. Only one item did not reach the threshold of 0.40. Floor effects were not observed, but ceiling effects were marked on all K-FOSQ subscales except one. All domains of K-FOSQ were significantly correlated with the corresponding scores of all tested instruments. The global K-FOSQ had a strong correlations (r > 0.50) with ESS and Sleep Problem Index-2 of MOS-Sleep, and had medium-sized correlations (r = 0.40–0.50) with BDI and SF-36 total scores. The K-FOSQ global and subscales did discriminate between participants with and without daytime sleepiness, but not between simple snorers and OSA patients.

Validation of the World Health Organization’s Quality of Life Questionnaire with Parents of Children with Autistic Disorder

The World Health Organization's Quality of Life Questionnaire-BREF (WHOQOL-BREF) has been used in many studies that target parents of children with Autistic Disorder. However, the measure has yet to be validated and adapted to this sample group whose daily experiences are considered substantially different from those of parents of children with typical development and parents of children with other disabilities. Therefore, this study was designed to examine the psychometric properties and the theoretical structure of the WHOQOL-BREF with a sample of 184 parents of children with Autistic Disorder. The factor structure for the WHOQOL-BREF was examined using exploratory and confirmatory factor analyses. Our analyses provided no evidence of a better model than the original 4-domain model. Nevertheless, some items in the measure were re-distributed to different domains based on theoretical meanings and/or clean loading criteria. The new model structure gained the measure's required validity with parents of children with Autistic Disorder.

Development of High-Content Gemcitabine PEGylated Liposomes and Their Cytotoxicity on Drug-Resistant Pancreatic Tumour Cells

The objective of this study was to develop high-content gemcitabine PEGylated liposomes to reverse gemcitabine resistance in pancreatic tumour cells. The mechanism of drug loading into liposomes was also investigated. To increase the drug entrapment efficiency (EE) and drug loading (DL), a novel passive loading approach named Small Volume Incubation method (SVI) was developed and compared to the reverse phase evaporation (REV) and remote loading methods. The in vitro cytotoxicity was evaluated using MIA PaCa-2 and Panc-1 cell lines. The EE for remote loading was 12.3 ± 0.3%, much lower than expected and a burst release was observed with the resultant liposomes. Using the optimized SVI method, increased EE (37 ± 1%) and DL (4%, w/w) were obtained. The liposomes (200 ± 5nm) showed minimal drug leakage, good stability, and significant improvement in cytotoxicity to the gemcitabine-resistant pancreatic cancer cell lines. Remote loading was not suitable for loading gemcitabine into liposomes. pKa > 4.6 for basic drugs and intra-liposomal precipitation of loaded compounds were suggested as an additional requirement to the current criteria for remote loading using ammonium sulphate gradient (pKa < 11). High DL is essential for liposomes to reverse gemcitabine resistance in pancreatic cell lines.

Visualization of Multiaxial Stress/Strain State and Evaluation of Failure Life by Developed Analyzing Program under Non-Proportional Loading

This study presents definitions of principal stress/strain range and mean stress/strain introduced by utilizing Itoh-Sakane criterion for multiaxial loading including non-proportional loading, and shows the method of calculating the non-proportional factor which expresses the severity of non-proportional loading under the multiaxial 3D loading. This paper also shows a method of visually presenting the stress/strain, the non-proportionality of loading and the damage evaluation.