Intermediate Support Research Articles

An analytical method for free vibrations of functionally graded cylindrical shells with arbitrary intermediate ring supports

An analytical method is presented to study free vibrations of functionally graded material (FGM) cylindrical shells with arbitrary intermediate ring supports. Material properties continuously vary in thickness direction in accordance with the four-parameter power-law distributions in terms of volume fractions of constituents. To establish the final governing equation, the shell is firstly divided into several shell segments according to locations of ring supports. Based on the first-order shear deformation theory (FSDT), differential equations about displacements are solved by expanding displacements as exponential functions in axial direction and Fourier series in circumferential direction. Correspondingly, five displacements and five forces at any cross section of segments are further expressed as 10 unknown coefficients for every circumferential mode number. The artificial spring technique is adopted to restrain displacements at boundaries and ring supports, and all segments are assembled to the overall shell through continuity conditions. To test the validity of the developed model, natural frequencies and mode shapes of several homogenous and FGM cylindrical shells with/without ring supports are compared with appropriate ones in the literature or calculated by finite element method (FEM), which demonstrates high accuracy and wide application of the proposed method. Furthermore, effects of ring supports and material parameters are analyzed. The results reveal that restraining radial and/or circumferential displacements at ring supports significantly affects natural frequencies, but mode shapes are mainly affected by radial displacements. In addition, natural frequencies of the FGM shell obviously vary with the power-law exponent, whereas the corresponding mode shapes almost keep unchanged.

Prehospital care providers' understanding of responsibilities during a behavioural emergency.

BackgroundPrehospital emergency care providers are frequently called to assist with the management of mental healthcare users (MHCUs). The Mental Health Care Act no. 17 of 2002 regulates mental healthcare in South Africa, but the act fails to consider the responsibilities of prehospital emergency care providers in the provision of mental healthcare. Rather South African Police Services were given authority over the well-being of a MHCU in the prehospital setting.AimTo investigate prehospital emergency care providers’ understanding of their responsibilities towards MHCUs and the community during the management of behavioural emergencies.SettingThe research was carried out at prehospital emergency care providers from the three main levels of care, currently operational within the boundaries of Pretoria, South Africa.MethodsA grounded theory qualitative study design was chosen using semi-structured focus groups for each level of prehospital emergency care – basic life support (BLS), intermediate life support (ILS) and advanced life support (ALS). Data from each focus group were collected through audio recordings and transcribed and analysed using a framework approach.ResultsA total of 19 prehospital emergency care providers participated; two focus group interviews were performed for each level of care. The BLS focus groups each consisted of two participants. The ILS focus groups consisted of three participants each, and the ALS focus groups consisted of six and three participants. Four key themes were identified: perceptions of behavioural emergencies, responsibilities, understanding of legislation and barriers experienced.ConclusionParticipants placed high value on their moral and medical responsibilities towards MHCUs, which they described as ensuring the safety of themselves, MHCUs and the community; preventing further harm; and transporting MHCUs to an appropriate healthcare facility. There was a desire for revision of legislation, better education, skill development and awareness of mental healthcare in the prehospital emergency care setting.

Comorbid mental disorders and quality of life of people with epilepsy attending primary health care clinics in rural Ethiopia.

Evidence from high-income countries demonstrates that co-morbid mental disorders in people with epilepsy adversely affect clinical and social outcomes. However, evidence from low-income countries is lacking. The objective of this study was to measure the association between co-morbid mental disorders and quality of life and functioning in people with epilepsy. A facility-based, community ascertained cross-sectional survey was carried out in selected districts of the Gurage Zone, Southern Ethiopia. Participants were identified in the community and referred to primary health care (PHC) clinics. Those diagnosed by PHC workers were recruited. Co-morbid mental disorders were measured using a standardised, semi-structured clinical interview administered by mental health professionals. The main outcome, quality of life, was measured using the Quality of Life in Epilepsy questionnaire (QOLIE-10p). The secondary outcome, functional disability, was assessed using the 12-item World Health Organization Disability Assessment Schedule (WHODAS-2). The prevalence of comorbid mental disorders was 13.9%. Comorbid mental disorders were associated with poorer quality of life (Adjusted (Adj.) β -13.27; 95% CI -23.28 to-3.26) and greater disability (multiplier of WHODAS-2 score 1.62; 95% CI 1.05, 2.50) after adjusting for hypothesised confounding factors. Low or very low relative wealth (Adj. β = -12.57, 95% CI -19.94 to-5.20), higher seizure frequency (Adj.β coef. = -1.92, 95% CI -2.83 to -1.02), and poor to intermediate social support (Adj. β coef. = -9.66, 95% CI -16.51 to -2.81) were associated independently with decreased quality of life. Higher seizure frequency (multiplier of WHODAS-2 score 1.11; 95% CI 1.04, 1.19) was associated independently with functional disability. Co-morbid mental disorders were associated with poorer quality of life and impairment, independent of level of seizure control. Integrated and comprehensive psychosocial care is required for better health and social outcomes of people with epilepsy.

Vibration of an axially loaded heterogeneous pinned-pinned beam with an intermediate roller support

The present paper is devoted to the issue of what effect the axial load (compressive or tensile) has on the eigenfrequencies of a heterogeneous pinned-pinned beam with an intermediate roller support (called a PrsP beam). This problem is a three point boundary value problem (eigenvalue problem) associated with homogeneous boundary conditions. If the Green functions of the three point boundary value problem (BVP) are known the eigenvalue problem that provide the eigenfrequencies for the beam loaded axially can be transformed into an eigenvalue problem governed by a homogeneous Fredholm integral equation. The later eigenvalue problems can be reduced to an algebraic eigenvalue problem which then can be solved numerically by using an effective solution algorithm which is based on the boundary element method.

Calculation method steel reinforced concrete continuous bridge spans with two reinforced concrete slabs on the effect of concrete shrinkage

The article is considered calculation method steel reinforced concrete continuous bridge spans with two reinforced concrete slabs on the effect of concrete shrinkage. For long-term processes that must be considered when calculating the span structures of bridges, besides creep, concrete shrinkage applies. Object of study: composite steel and concrete span beam bridge with two reinforced concrete slabs. Purpose: to develop a calculation method the cross section steel reinforced concrete bridges with two reinforced concrete slabs on the effect of concrete shrinkage considering concrete creep. Continuous spans of steel reinforced concrete bridges with two reinforced concrete slabs over intermediate supports much more economically, in terms of metal consumption, compared to steel reinforced concrete bridges with one concrete slab. Cross section of a reinforced reinforced concrete beam consists of a steel part that combined with two reinforced concrete slabs. The article presents the results of the calculation of continuous steel-concrete superstructure of a road bridge with two reinforced concrete slabs by the above method.

Strength, Flexural Rigidity and Aerodynamic Stability of Fiberglass Spans in Pedestrian Suspension Bridge

At present, it is highly relevant to improve the safety of transport and pedestrians by crossing their paths at different levels. At the same time, to cross wide highways, it is rational to design pedestrian bridges without intermediate supports, namely suspension and cable-stayed bridges. In addition, numerous studies have confirmed the feasibility of using fiber-reinforced plastic (FRP) as a material for load-bearing structures. However, in order to massively introduce FRP suspension bridge designs into production, it is necessary to improve the method of designing suspension bridges, which has been used mainly on steel and reinforced concrete bridges for decades. Therefore, the paper describes theoretical and experimental studies of strength, flexural stiffness (calculations are made taking into account geometric nonlinearity), as well as the aerodynamic stability of structures of single-span suspension bridges with main beams made of polymer composite materials. As a result of the research, the feasibility of designing FRP bridge structures within the framework of the adaptation concept was confirmed. The obtained conclusions will serve to improve the method of calculating suspension bridges with main beams made of polymer composites.

Determination of dynamic parameters of the elastically supported beam system model by optical and numerical methods

The article describes the design of a test facility that designed and manufactured by the authors for parametric studies of the features of free and forced vibrations of elastically supported dynamical systems. The results of a full-scale experiment are presented in the article, during which a frequency analysis of a beam with an intermediate elastic support is performed. Measurements are made with the use of the optical method of determining the movements and inductive sensors. A finite element model of the test facility was built in the Midas NFX environment with the aim to verify and evaluate the results. The results of the modal analysis performed for the finite element model of the test facility are compared with the natural frequency spectra obtained as a result of experiments. Conclusions are drawn about the prospects of using the test facility, the accuracy of the measuring equipment used, and about the way the finite element model built in the Midas NFX program environment corresponds to the full-scale model of the dynamic system in terms of its dynamic characteristics.

The accuracy of Bloemfontein-based Emergency Medical Services providers in recognising sepsis

Background: Sepsis is considered a severe life-threatening medical emergency and globally carries a high mortality. Research suggests early recognition of sepsis can lead to early initiation of treatment and effective communication of this condition to the receiving facility by pre-hospital emergency care (PEC) providers. Depending on system operations, this has been shown to improve patient outcomes. However, sepsis often presents non-specifically, and in the absence of validated pre-hospital sepsis screening tools, less than half of sepsis patients seen by PEC providers are recognised. This study aimed to determine the accuracy with which Bloemfontein-based PEC providers recognise sepsis in a series of patient vignettes. Methods: A series of seven case vignettes were presented to a convenient sample of advanced life support (ALS) and intermediate life support (ILS) PEC providers. The PEC providers were asked to review each vignette and indicate whether the patient described had sepsis or not. The vignettes consisted of a clinical case description with signs and symptoms of patients presenting with or without sepsis, and images were shown where relevant. Elements of the Robson Prehospital Severe Sepsis Screening (RPSS) tool were used to populate the sepsis vignettes. Results: A total of 27 ILS and ALS PEC providers in the Bloemfontein area partook in the research study. Thus, a total of 189 vignettes were evaluated for sepsis. PEC providers, both ILS and ALS, recognised sepsis with a sensitivity of 69.63% and a specificity of 37.04% (PPV 73.44%, NPV 32.79%), indicating an accuracy of 60.32%. Although all participants mentioned some motivations for their answers, none of the participants gave specific cut-off value ranges at which point they would suspect sepsis. Conclusion: This vignette-based study found that PEC providers can recognise sepsis with modest accuracy, echoing previous work on this topic. In addition, the study provides a platform for similar studies, which, in turn, could aid in the development of a validated, pre-hospital sepsis screening tool.

Analysis of the stress state of the ribbed-ring metal dome under different methods of installation

A computer model of the frame of a ribbed-ring metal dome of steel I-beams with a span of 30,3 m and a height of 7,5 m with rigid connections at the joints have been developed. Based on the design scheme, auxiliary models of a partially complete dome frameworks were designed to study alternative installation methods, which differ from each other in the location scheme of temporary supports with hinge joints of bar elements over them. The installation computer models utilized the three schemes of temporary supports: central support, central support and 1 circular row of intermediate supports, central support and 3 circular rows of intermediate supports. Computer calculations were performed for the design model of the dome framework and for all installation models to evaluate the impact of the self-weight of the dome on the stress state of the elements of its framework. As a result of the research, graphs and diagrams were created, which reflect the level of installation stresses in the meridional ribs in comparison with their values in the design scheme. The necessity to perform calculations of the dome frameworks during the design according to the installation conditions is noted.

Research on bearing jacking method of steel -concrete composite beam bridge

There are plenty of advantages of steel-concrete composite beam bridges. However, Transverse cracks in composite girder bridges usually appear because of the tensile stresses in the concrete deck induced by the negative bending moment at the intermediate supports of continuous composite girder bridges. There are many measures to reduce the tensile stress in the negative bending moment zone of steel-concrete composite beams. At present, bearing jacking method is used more and more in engineering. Taking a composite beam in Shaanxi province as an example, this paper studies the influence of jacking amount and span number on the improvement effect of bearing jacking method. The improvement of stress level of concrete deck in negative moment zone of steel-concrete composite beam bridge is studied and analysed which puts forward relevant engineering solution.

An Effective Algorithm for Mining Indirect Association Rules

In order to solve the problem that it is necessary to scan the database many times and produce unnecessary frequent itemsets in the process of mining indirect association rules, a new algorithm FPI-mine based on FP-Tree is designed to mine the indirect association rules in transaction database. Firstly, FP-Tree is constructed, and then the indirect item pairs and intermediate support sets of all frequent items are found. Finally, all the indirect association rules are obtained by mining algorithm. It can directly mine indirect association rules without generating all frequent itemsets. Finally, the effectiveness of the algorithm is verified by experiments.

Electronic structure modelling of the edge-functionalisation of graphene by MnxOy particles.

The use of graphenic carbon is attractive as a basal or intermediate support for catalytic particles in advanced catalytic electrodes. This popularity is motivated by its excellent electrical properties and ability to form foliated conformal coatings of exceptional surface area and flexibility. Surface- and edge-functionalisation of graphene sheets affords diverse routes to the covalent attachment of candidate catalytic species. Of particular interest to advanced water oxidation is the possibility of covalent attachment of MnxOy species partially recapitulating the chemistry of the Mn4O5Ca active site of Photosystem II (PSII), which achieves the four-electron oxidation of water under physiological conditions. Here, we report aperiodic density functional theory (DFT) investigations of candidate attachment geometries for a variety of manganese oxide particles to graphene sheets. We find that the flexibility of graphene sheets as well as the conformational degrees of freedom of candidate edge functionalisation permits a large variety of realistic attachment geometries that can act as attachment sites for molecular manganese-oxide species or nuclei for the growth of periodic manganese oxides. We find that substantially simplified models of graphene attachment afford an excellent compromise between computational efficiency, tractability, and accuracy, and characterise the accuracy of these models in detail.

Buckling Analysis of Intermediately Supported Nanobeams via Strain Gradient Elasticity Theory

Buckling of axially loaded cantilever nanobeams with intermediate support have been studied in the current study. Higher order size dependent strain gradient theory has been utilized to capture the scale effect in nano dimension. Minimum total potential energy formulation has been used in modeling of nanobeam. Approximate Ritz method has been applied to the energy formulation for obtaining critical buckling loads. Position of the intermediate support has been varied and its effect on the critical buckling load has been investigated in the analysis. Mode shapes in critical buckling loads have been shown for various intermediate support positions. Present results could be useful in design of carbon nanotube resonators.

Effect of spring mid-support condition on the vibrations of the axially moving string

In this study, the axially moving string with spring-loaded middle support is discussed. The supports assumed as simple support on the string both ends. The intermediate support shows the characteristics of the spring. The string velocity is accepted as harmonically varying around a mean value. The Hamiltonian principle is used to find the equations of motion. The equations of motion become nonlinear, considering the nonlinear effects caused by string extensions. The equations of motion and boundary conditions are become dimensionless by nondimensionalization. Approximate solutions were found by using multiple time scales which is one of the perturbation methods. By solving the linear problem that is obtained by the first terms of the perturbation series, the exact natural frequencies were calculated for the different locations of the mid-support, various spring coefficients, and various axial velocity values. The second-order nonlinear terms reveal the correction terms for the linear problem. Stability analysis is carried out for cases where the velocity change frequency is away from zero and two times the natural frequency. Stability boundaries are determined for the principal parametric resonance case.

Electromechanical modeling and analysis of a piezocomposite multi-point loaded beam vibration energy harvester

In this paper, vibration energy harvesting from a piezocomposite beam with unconventional boundary conditions is investigated. The beam in consideration has multi-point constraints and consequently has concentrated multi-point loading along its length. It is shown that the natural frequencies, strain uniformity along the beam, and strain node positions can be adjusted by shifting the support locations, allowing for a significant range of mechanical tuning. To model the electromechanical system, the Euler-Bernoulli beam assumptions are adopted, and by Hamilton’s principle and Gauss’ law, the governing equations are derived. Frequency response functions of the output voltage and beam transverse displacement are solved for harmonic base excitation, and the maximum output power is calculated both numerically and analytically. A set of experimental results are used to validate the model. A detailed parametric analysis is conducted by varying tunable system parameters such as resistive load, tip mass, and the intermediate support location. All interesting operational conditions of the system, and the corresponding tuning parameters are quantified. It is shown that the multi-point loaded beam concept can produce higher strain-normalized-output-power when compared to a cantilevered or a simply supported beam.

Myocardial Substrate Oxidation and Tricarboxylic Acid Cycle Intermediates During Hypothermic Machine Perfusion

BackgroundThe optimal substrate for hypothermic machine perfusion preservation of donor hearts is unknown. Fatty acids, acetate, and ketones are preferred substrates of the heart during normothermic perfusion, but cannot replete the tricarboxylic acid (TCA) cycle directly. Propionate, an anaplerotic substrate, can replenish TCA cycle intermediates and may affect cardiac metabolism. The purpose of this study was to determine myocardial substrate preferences during hypothermic machine perfusion and to assess if an anaplerotic substrate was required to maintain the TCA cycle intermediate pool in perfused hearts. MethodsGroups of rat hearts were perfused with carbon-13 (13C)-labeled substrates (acetate, β-hydroxybutyrate, octanoate, with and without propionate) at low and high concentrations. TCA cycle intermediate concentrations, substrate selection, and TCA cycle flux were determined by gas chromatography/mass spectroscopy and 13C magnetic resonance spectroscopy. ResultsAcetate and octanoate were preferentially oxidized, whereas β-hydroxybutyrate was a minor substrate. TCA cycle intermediate concentrations except fumarate were higher in substrate-containing perfusion groups compared with either the no-substrate perfusion group or the no-ischemia control group. ConclusionsThe presence of an exogenous, oxidizable substrate is required to support metabolism in the cold perfused heart. An anaplerotic substrate is not essential to maintain the TCA cycle intermediate pool and support oxidative metabolism under these conditions.

Experimental Behavior of the Curved Continuous Twin I-Girder Composite Bridge with a Precast Concrete Slab Subjected to Bending, Shear, and Torsion

In order to investigate the mechanical behavior, ultimate load carrying capacity, and failure mode of the intact curved continuous twin I-girder composite bridge (TGCB) with a precast concrete slab, one curved continuous composite bridge model with a scale ratio of 1 : 5 of a prototype bridge was designed and manufactured considering the influence of the construction sequence. Four symmetric point loads’ test was carried out. In this paper, load-deflection relationship and strain development of steel girders, concrete slab, and reinforcement at key sections were tested and analyzed. Failure mode, crack development, and major crack width at the top surface of the concrete slab in the hogging moment region were also reported. The experimental results demonstrated that the load capacity under the initial cracking level, cracking level with the width of 0.2 mm, and steel girder yielding state is about 1.7, 5.0, and 6.3 times of the design load, respectively. Due to the influence of curvature, the stiffness of the external girder is less than that of the internal girder. However, the ultimate bearing capacity is basically the same, approximately 13.6 times of the design load. During the loading process, plastic hinge was first observed at the intermediate support section as a result of the hogging moment which should be emphasized in design. The local buckling took place after yielding, indicating a class 2 section according to Eurocode 4. In addition, the TGCB had good ductility since the displacement ductility coefficients of the external and internal girders were 4.40 and 4.06, respectively.

Preliminary Study on the Design of Structures with a Responsive External Post-tensioning System

External post-tensioning has proven to be an effective solution to introduce intermediate supports in structures in order to decrease their spans and to allow a more efficient distribution of bending moments. This leads to important savings in terms of material. However, this increase in effectiveness is achieved only for a specific loading, which generally corresponds to the permanent load distribution. This paper introduces the possibility of expanding the benefits of this technique to situations where relevant live loads act through the use of a responsive external post-tensioning system. The responsive behaviour is materialized through an actuator located between the beam and the post-tensioning system. After a brief overview of the existing responsive structures, this research studies the static structural behaviour of responsive externally post-tensioned structures. Furthermore, the main design variables are parametrically analysed and the applicability of the system is evaluated with the construction of a small-scale prototype. Finally, results are discussed and the effectiveness of this approach in terms of material savings is claimed.

The investigation of the stress-strain state of beam crossings with a truss-form supporting element of the operating pipeline

The areas of application and advantages of the over-ground piping or pipe section layout are given. The classification according to the design features of the most common systems of overhead pipeline crossings on the basis of generalization of scientific publications and experience of pipeline construction are considered. The authors indicate the ranges of the effective spans for rectilinear single-span and multi-span crossings without compensators of longitudinal strains (with the fixed ends) and also in multi-span systems with compensators depending on the diameter of pipes, nominal pipe wall thickness and brand of pipe steel for gas, oil and oil-products pipelines respectively. The description of the design of beam systems of overhead pipeline crossings with a truss-form supporting element of the operating pipeline is given and the procedure for estimating their stress-strain state is suggested. According to the constructed cargo and unit calculation schemes of the truss with a cross-section in the form of an isosceles triangle (height – 3 m, width – 2.02 m) the stiffness coefficients of elastic-malleable supports is determined. The selection of cross-sections of truss members is carried out, the required deflections of the pipeline and the emerging internal force factors (bending moments and reactions of elastic-malleable supports) at the points where the pipeline rests on the truss are found. The strength of the pipeline to the action of the maximum bending moment is checked and the possibility of the cross-water layout of the beam crossing of the gas pipeline is shown. This is the gas pipeline with the length of . It has compensators with a truss-form supporting element which eliminates the use of intermediate supports. Thus, it was shown that the truss makes it possible to double or triple the length of the span using no intermediate supports and preserving sufficient horizontal rigidity.

Parenting styles revisited: A longitudinal person-oriented assessment of perceived parent behavior

The pernicious consequences of parent psychological control are well-established. Parenting style classification schemes, however, typically exclude this behavioral practice, focusing instead on demandingness and responsiveness. The present study applies a person-oriented approach to the classification of parenting styles, taking into account psychological control. Lithuanian adolescents (239 girls, 215 boys; M age = 15.14 at the outset) completed questionnaires at annual intervals across high school, describing parent behavioral control, support, and psychological control. Longitudinal multidimensional latent class growth analysis (LCGA) yielded four parenting style categories. Two conventional groups emerged: authoritative (highest behavioral control and support, lowest psychological control) and indulgent (high support, low behavioral control, lowest psychological control). Two additional groups emerged in lieu of an authoritarian category: enmeshed (high behavioral control and psychological control, intermediate support) and affectively controlling (highest psychological control, lowest behavioral control and support). Children of authoritative parents reported favorable adjustment on a host of indicators, including behavior problems, school engagement, character, self-esteem and interpersonal caring and connection; children of affectively controlling parents reported the poorest adjustment on all variables measured.