Partially Loaded Research Articles

Assessment of a mixed-mode vertical solar dryer for experimental turmeric drying

Solar drying, an eco-friendly and sustainable approach harnesses solar radiations to remove moisture from a drying commodity, thereby preventing its spoilage and extending shelf life. Turmeric (Curcuma longa), a popular herb is being used for centuries in Ayurveda as a traditional medicine. Since, fresh turmeric contains 80–90 % moisture content, therefore, it is quite difficult to store for a longer period. An innovative and compact mixed-mode vertical solar dryer (MVSD) with a circular solar collector (solar tracking geometry) is developed and tested for turmeric slices drying under partial and fully loaded conditions. Turmeric samples of 2, 3 and 4 mm slices thicknesses were used for experimentation under partial loading condition. The thickness of the turmeric slices was observed to affect the performance of the MVSD. The drying rate and thermal efficiency were observed to be highest for 3 mm thick turmeric slices sample under partially loaded condition. The MVSD was further tested with full loading capacity for 3 mm thick turmeric slices drying under natural and forced convection (NC and FC), respectively modes. The drying behavior of turmeric slices was well described by Midilii-Kucuk model. Heat transfer coefficients and efficiency (thermal and exergy) were observed to be higher under FC mode. Embodied energy and energy payback time were observed as 554.44 and 585.53 kWh; and 4.39 and 4.55 years under NC and FC modes, respectively. Annualised cost and payback period were observed to be desirable for NC mode.

Fatigue and monotonically-loaded reinforced concrete specimens subjected to partial area loading

The degradation of concrete structures is often due to the continuous application of compressive fatigue loads. Understanding of concrete behaviour in different environmental conditions and under especial fatigue loading arrangements, particularly in cases where the loaded area is smaller than loaded element, herein referred to as partially loaded area, is of utmost importance to make a realistic prediction of the concrete fatigue life for a reliable design of civil engineering infrastructure. This paper focuses on investigating the fatigue performance of reinforced concrete specimens subjected to partially loaded areas, considering the influences of steel fibres, reinforcement arrangement, and the environmental factor of water submergence. A typical example of a partially loaded concrete component subjected to fatigue loading is circular spread footings used as concrete foundations for typical wind turbines. In these types of elements, the compressive strength of the concrete can be enhanced due to the confinement provided by way of lateral restraint stemming from surrounding concrete and reinforcement. However, design codes primarily address static loading and lack specific criteria for fatigue loading in these partially loaded regions. To address this research gap, results from a comprehensive experimental study, which in total included 111 concrete specimens subjected to monotonic loading and 25 specimens tested under cyclic loading, were used to study this problem. The investigation aimed to evaluate the effects of steel fibres and reinforcement arrangement on both static and fatigue capacity. Additionally, the impact of submerging concrete structures in water on their fatigue performance was examined, revealing a decrease in their fatigue life. The experimental results demonstrated that the presence of steel fibres and splitting reinforcement significantly increased both static and fatigue capacity. Most current design codes neglect the environmental factor of water submergence, leading to reduced fatigue capacity in concrete structures. Consequently, the validity of the design codes DNV-OS-C502 and fib Model Code 2010 was evaluated, and a new environmental factor for partially loaded areas subjected to cyclic loading is proposed. To evaluate the experimental results and understand the mechanical response, nonlinear finite element analyses were conducted using a smeared-crack continuum modelling procedure coupled with high cycle fatigue material models to assess its applicability for estimating fatigue performance of partially loaded reinforced concrete elements. It was found that a plane stress modelling procedure was capable of estimating fatigue capacity for dry concrete components, however, overestimated the fatigue capacity of wet concrete components.

In Vivo Investigation of 3D-Printed Calcium Magnesium Phosphate Wedges in Partial Load Defects.

Bone substitutes are ideally biocompatible, osteoconductive, degradable and defect-specific and provide mechanical stability. Magnesium phosphate cements (MPCs) offer high initial stability and faster degradation compared to the well-researched calcium phosphate cements (CPCs). Calcium magnesium phosphate cements (CMPCs) should combine the properties of both and have so far shown promising results. The present study aimed to investigate and compare the degradation and osseointegration behavior of 3D powder-printed wedges of CMPC and MPC in vivo. The wedges were post-treated with phosphoric acid (CMPC) and diammonium hydrogen phosphate (MPC) and implanted in a partially loaded defect model in the proximal rabbit tibia. The evaluation included clinical, in vivo µ-CT and X-ray examinations, histology, energy dispersive X-ray analysis (EDX) and scanning electron microscopy (SEM) for up to 30 weeks. SEM analysis revealed a zone of unreacted material in the MPC, indicating the need to optimize the manufacturing and post-treatment process. However, all materials showed excellent biocompatibility and mechanical stability. After 24 weeks, they were almost completely degraded. The slower degradation rate of the CMPC corresponded more favorably to the bone growth rate compared to the MPC. Due to the promising results of the CMPC in this study, it should be further investigated, for example in defect models with higher load.

Partially loaded areas in reinforced concrete: Experimental campaign and model validation

This paper presents the results of a comprehensive experimental campaign investigating the structural behaviour of concrete blocks subjected to partial area loading. A total of 62 concrete blocks were loaded up to failure by applying a compressive load over a limited area. The campaign focused on plane cases of partial area loading, i.e. the load was applied over the (almost) entire block length and thus dispersed mainly in one direction. The test parameters included (i) the specimen geometry; (ii) the size of the loaded area; (iii) the concrete strength; (iv) the conventional reinforcement ratio, layout, and detailing; and (v) the steel fibre content. Modern measuring techniques were applied to gain insight into the crack development, the reinforcement activation, and the contact pressure distribution over the loaded area. The test results, together with experimental data found in the literature, substantiate the fundamental mechanical behaviour identified in previous theoretical studies by the authors. It is shown that the Dual-Wedge and Dual-Cone stress fields presented in the companion paper can accurately reproduce the influence of the investigated test parameters. Moreover, the bearing capacity predictions by these stress fields correlate significantly better with the experimental data than existing design rules implemented in current design codes.

Partially loaded areas in reinforced concrete: Mechanical modelling

The introduction of high compressive forces on concrete members over limited contact areas is a common problem in engineering practice. Despite extensive research, a knowledge gap persists in the mechanical understanding of this seemingly simple problem. This paper first summarises the state of the art regarding the bearing capacity problem in structural concrete and then introduces two new stress field solutions for plane and axisymmetric cases of partial area loading. Contrary to most existing design approaches, which are purely empirical, the models proposed build on consistent mechanical bases that ensure safe design. The stress fields consider consistently the beneficial effect of reinforcement and the multiaxial compressive strength of concrete. Moreover, they enable the flow of forces to be followed through the structure, resulting in consistent dimensioning and detailing of the reinforcement. The comparison with existing design approaches shows that the stress fields predict significantly higher bearing capacities, enabling the design of more efficient and sustainable structures. In a companion paper, the stress fields are validated with published experimental data and an extensive test campaign conducted by the authors.

Partial loading of performance reference compounds in passive samplers and its effect on the fractional approach to steady state

Passive sampling for hydrophobic organics in soils and sediments is typically accomplished by measuring the equilibrium accumulation of the target compounds onto a sorbing polymer. Because the samplers do not often achieve equilibrium in the environment, the release of performance reference compounds (PRCs) pre-loaded on the sampler is used to estimate the extent of equilibrium uptake of a similar target compound. In this work, we evaluate the effect of non-equilibrium loading of PRCs on the estimated equilibration of target compounds. A numerical transport model considering both internal and external mass transfer resistances to the polymer during loading from a finite reservoir was constructed to predict PRC distribution polymer sheets. An analytical internal diffusion, external mass transfer limited model is then employed to simulate the release of the PRCs and predict both the apparent and actual approach to equilibration for the uptake of target compounds. Partial equilibration during loading of PRCs does not lead to inaccuracies in target compound equilibration except when internal resistances control both PRC release and target compound uptake, under which conditions the PRCs overestimate the extent of equilibration of target compounds. This is likely to occur during short PRC loading times (e.g., <1 month) and thick polymer sheets (e.g., >100 µm in thickness). If external mass transfer resistances control PRC release and target compound uptake, even partially loaded PRCs can accurately indicate the extent of equilibration of target compounds as long as the initial PRC loading is adequately characterized.

Experimental and numerical investigations of concrete-filled stainless steel tube stub columns under axial partial compression

This paper presents a thorough experimental and numerical investigation into the structural performance and load-carrying capacities of circular concrete-filled stainless steel tube (CFSST) stub columns under axial partial compression. The experimental programme was carried out on 3 fully loaded (reference) circular CFSST stub column specimens and 15 partially loaded circular CFSST stub column specimens, with a series of material and geometric parameters (including the concrete grade, the stainless steel tube size and the area and shape of the partial compression region) varied. Analysis of the obtained test results revealed that the partial compression area ratio, defined as the ratio of the concrete gross area to the partially loaded area, and the confinement factor, given as the steel tube to concrete plastic compression resistance ratio, are the two key factors influencing the structural behaviour and load-carrying capacities of circular CFSST stub columns subjected to partial compression. The testing investigation was supplemented by a systematic finite element (FE) modelling study, where the numerical models were firstly developed and validated against the experimentally derived results and then employed to conduct parametric studies for the purpose of expanding the experimental data pool over a broader range of partial compression area ratios and confinement factors. In the absence of the established codified design provisions for CFSST stub columns subjected to partial compression, the corresponding design rules for partially loaded concrete-filled carbon steel tube stub columns, as given in the European code and American specification, were evaluated for CFSST stub columns under partial compression load, and shown to result in both conservative and scattered resistance predictions. Other recently developed proposals for partially loaded concrete-filled carbon steel tube stub columns were also assessed for CFSST stub columns, indicating a high level of design accuracy on average but with many unsafe resistance predictions. Finally, a new design approach was developed specifically for CFSST stub columns under partial compression, and shown to yield precise, consistent and safe-sided resistance predictions through comparing against the test and FE results.

Mass Transfer Kinetics of CO2 in Loaded Aqueous MEA Solutions

The kinetic mass transfer between partially loaded MEA aqueous solutions and CO2 were measured in absorption experiments over a temperature range 303.15 – 313.15K, MEA concentrations 3M and 5M, and a partial loading range 0.05 –0.30mol/mol. The measurements were conducted by a stirred cell using batch operation for both liquid and gas. The pseudo first order reaction rate constant kps and the 2nd order reaction rate constant k2 were obtained. The effects of the pre-loading of the solutions on kps and k2 were investigated.

Compact Wideband Loop Antenna Partially Loaded With Mu-Negative Metamaterial Unit Cells for Directivity Enhancement

A wideband and unidirectional loop antenna partially loaded with mu-negative (MNG) metamaterial unit cells is presented. To reduce the electrical size of the antenna, its first resonance is formed by capacitively loading a conventional one-wavelength loop antenna to excite the mu-zero resonance that is independent of the resonator's size. As a result of partial loop loading using properly designed and distributed slots, the amplitude of the surface current can be engineered to be higher in the feeding arm while achieving a zero phase shift along each arm of the loop structure. Consequently, unidirectional radiation with a moderate front-to-back ratio (FBR) is achieved without using any reflectors. Moreover, as a result of the capacitive loading, the loop antenna is divided into an array of dipoles that are excited with a 90° phase difference, enabling unidirectional radiation at the loop-mode resonance. To both enhance the impedance matching of the antenna at lower frequencies and excite an additional resonance, a strip patch is added in the vicinity of the loop. The proposed structure is smaller by 80% than similar MNG loaded loops and achieves a wide fractional bandwidth of 52% (0.64–1.1 GHz) with a peak FBR and gain values of 12 dB and 3.2 dBi, respectively.

Partially Loaded Magnetoelastic Sensors With Customizable Sensitivities for Large Force Measurements

Magnetoelastic sensors are typically made of strips of magnetostrictive materials that efficiently convert magnetic energy into mechanical energy, and vice versa. When exposed to an ac magnetic field, the sensor vibrates, producing a secondary magnetic flux that can be remotely detected. If the frequency of the ac magnetic field matches the sensor's resonant frequency, the magnetic-mechanical energy conversion is optimal, resulting in a large secondary magnetic flux. The magnetoelastic sensor has been used to monitor physical parameters relevant to force, such as mass or stress, since its resonant frequency, indirectly through the $\Delta E$ effect, is dependent on the magnitude of an applied force. Typically, the applied force must be significantly less than the weight of the sensor or it completely dampens the sensor's resonance. Presented here is the design and operation of a magnetoelastic sensor capable of monitoring large forces by applying partial loading to strategic points on a sensor. The characterization and analysis of this new magnetoelastic sensor is presented along with numerical modeling to illustrate the proposed sensing mechanism. Additionally, an array of magnetoelastic sensors were deployed to demonstrate monitoring of force loading on the lock-in portion of a lock-in style lower limb prosthetic sleeve.

Method for verifying the air kerma strength of I-125 plaques for the treatment of ocular melanoma.

The purpose of this work was to develop a method for easily verifying that the activity or air kerma strength of pre‐assembled eye plaques, used in the treatment of ocular melanomas, agrees with the activity or air kerma strength called for in the treatment plan. A Capintec CRC‐7 Dose Calibrator with its standard vial/syringe sample holder was used to measure the activity of pre‐assembled COMS and Eye Physics EP917 eye plaques using IsoAid Advantage I‐125 seeds. Plaque activity measurements were made by placing the plaque face up in the center of a 5 cm tall Styrofoam insert in the source holder. Activity measurements were made with the source holder rotated to four angles (0°, 90°, 180°, and 270°). The average of these four values was converted to air kerma strength and divided by the assay air kerma strength, from the NIST traceable source calibration, and decayed to the plaque measurement date, to determine a plaque calibration factor. The average of the calibration factors for each plaque type was used to establish a calibration factor for each plaque type. Several partially loaded plaque configurations were included in this study and different methods were used to determine the effects of partial loading. This verification method is easy to implement with commonly available equipment and is effective in identifying possible errors. During this two‐year study, the air kerma strength of 115 eye plaques was checked and 11 possible errors were identified.PACS number: 87.55.Qr

Axisymmetric large deflection analysis of fully and partially loaded shallow spherical shells

Geometrically non-linear axisymmetric bending of a shallow spherical shell with a clamped or a simply supported edge under axisymmetric load was investigated numerically. The partial load was introduced by the Heaviside step function, and the solution was obtained by the finite difference and the Newton-Raphson methods. The thickness of the shell was considered to be uniform and the material was assumed to be homogeneous and isotropic. Sensitivity analysis was made for three geometrical parameters. The accuracy of the algorithm was checked by comparing the central deflection, the radial membrane stress at the edge, or the transverse shear force with the solutions of plates and shells in the literature and good agreement was obtained. The main findings of the study can be outlined as follows: (i) If the shell is fully loaded the central deflection of a clamped shell is larger than that of a simply supported shell provided that the shell is not very shallow, (ii) if the shell is partially loaded the central deflection of the shell is sensitive to the parameters of thickness, depth, and partial loading but the influence of the boundary conditions is negligible.

Fluid‐structure interaction in porous media for loaded filter pleats

AbstractCurrently, the known simulation efforts with respect to fluid‐structure interaction (FSI) are mainly restricted to the study of flow interacting with deformable solid bodies. On the other hand, there is extensive literature on simulation of flow through porous media. In particular, algorithms and software for CFD simulations of filtration processes in the case of rigid filtration medium were presented earlier by Fraunhofer ITWM, see, e.g., [1, 2]. In these papers the deformation of the solid skeleton is neglected. In many cases of water filtration, filtration for hydraulic applications, and even in certain air filtration regimes, the fluid pressure can be quite high, and the deformation of the pleats can be an issue. The deflection of pleats and its effect on the filtration process merits examination because under operating conditions (and especially after a partial loading of the media) the pleats often cannot be anymore considered as rigid porous media. Therefore, in this paper, the deflection is considered for clean media, as well as for partially loaded media. A new model describing the coupled flow and deformation, and corresponding numerical results are presented. (© 2011 Wiley‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

물류센터의 팔렛합적 문제

In most distribution centers, products are received from the suppliers in units of pallet, stored in a rack, moved to the picking area for replenishment, picked according to customer orders, and shipped to customers. In some distribution centers, however, replenishment is made in not a whole pallet but only a portion of a pallet load, mainly due to the limited space in the order-picking area; as a result, partially loaded pallets occupy cells in the rack. As the number of slow-moving items increases, more cells are occupied by partially loaded pallets so that fewer empty cells are available for storing full, incoming pallets. This will necessitate the construction or leasing of additional storage space, which will entail significant cost. As an alternative, we propose pallet consolidation, which involves moving a partial load to another partially-loaded pallet in order to create one empty cell in the rack. In this paper, we define three pallet consolidation problems; formulate each problem as a binary integer programming model; and present heuristic algorithms for the problems. The average performance of each of the proposed heuristics is evaluated using simulation.

An Experimental Study on the Exhaust Emissions of a Partially Loaded Compressed Ignition Engine Fueled with Biodiesel Derived from Cottonseed Oil

The world energy demand is increasing rapidly due to the excessive use of the fuels but because of limited reserves, the researchers are now looking for alternative fuels. Another serious problem associated with the use of petroleum fuel is the increase in pollutants emissions. In this study, cottonseed oil methyl ester was added to diesel fuel by volume of 5% (B5), 20% (B20), and 50% (B50). Blends were used in a single cylinder, direct injection, air-cooled diesel engine at partial and full load condition. In experiments, the effects of cottonseed oil methyl ester ester-diesel fuel blend on the engine fuel consumption and exhaust emissions were investigated at 2,000 rpm of engine speed that most engines run on. At the tests, the effect of blends on fuel consumption, exhaust gases temperature, CO, NOx, SO2, and smoke opacity was clarified. The experimental results showed that cottonseed oil methyl ester can be substituted for the diesel fuel without any modifications in diesel engines.

농업용 트랙터의 연료 소비량 예측 모델

A mathematical model was developed to predict the fuel consumption rate consumed by agricultural tractors under arbitrary loaded conditions. The model utilizes the measured data on the fuel consumptions at the full load and at the rated engine speed with partial loads, which can easily be obtained from the official OECD tractor test reports. It was found from the analysis of the measured fuel consumption data that the fuel consumptions at two different speeds does not change with power. The model was developed based on this fact and validated with the measured data of the 159 tractor test reports. The fuel consumptions predicted by the model were compared with those measured under the partially loaded conditions specified in the official OECD tractor test code II. The percent errors of the predicted fuel consumptions were in a range from 0.36 to 2.86% which assured that the developed fuel consumption model can be used practically to predict the fuel consumptions at any speed and power combinations. It was also shown that the developed model predicts the fuel consumption rate better than the Grisso`s model.

Modified ${\rm TM}_{020}$ Mode of a Rectangular Patch Antenna Partially Loaded With Metamaterial for Dual-Band Applications

In this letter, the TM020 mode of a rectangular patch antenna is modified by partially loading a mu-negative (MNG) or double-negative (DNG) metamaterial block. With proper constitutive parameters and filling ratio, the electric fields at two radiating edges of the patch can be out of phase, and a broadside radiation pattern is achieved. A novel dual-band rectangular patch antenna loaded with a pair of conventional double-positive (DPS) and MNG metamaterial blocks is proposed as an application example of the modified TM020 mode. Good impedance matching and similar patterns with broadside radiation are achieved simultaneously at both operating frequencies with a single-layer single-patch fed by a single coaxial line. Simulation shows that the modified TM020 mode gives an efficient radiator with sufficient gain and very low level of cross polarization. Partial loading of a DNG metamaterial block is also discussed for some special dual-band applications.

Stability analysis of composite plates under localized in-plane load

Stability characteristics of isotropic and composite plates subjected to partial or concentrated compressive edge loads are investigated here using a four-noded shear-flexible quadrilateral high-precision plate-bending element. A complete cubic polynomial shape function is used to interpolate the in-plane displacements for better accuracy in capturing the high-stress zone near the locally distributed edge load. The influences of location and distribution of in-plane edge compression on the buckling load of composite plates are studied. The nonlinear governing equations based on von Kármán's assumptions are solved by Newton–Raphson technique to get the hitherto unreported postbuckling equilibrium paths of partially loaded plates made of isotropic, symmetric, and unsymmetric laminates. Marguerre's shallow-shell theory is employed to study the effect of sinusoidal imperfection on the nonlinear behavior of composite plates under partial in-plane load.

Core burnup calculation and accidents analyses of a pressurized water reactor partially loaded with rock-like oxide fuel

A rock-like oxide (ROX) fuel – light water reactor (LWR) burning system has been studied for efficient plutonium transmutation. For the improvement of small negative reactivity coefficients and severe transient behaviors of ROX fueled LWRs, a partial loading core of ROX fuel assemblies with conventional UO 2 assemblies was considered. As a result, although the reactivity coefficients could be improved, the power peaking tends to be large in this heterogeneous core configuration. The reactivity initiated accident (RIA) and loss of coolant accident (LOCA) behaviors were not sufficiently improved. In order to reduce the power peaking, the fuel composition and the assembly design of the ROX fuel were modified. Firstly, erbium burnable poison was added as Er 2O 3 in the ROX fuel to reduce the burnup reactivity swing. Then pin-by-pin Pu enrichment and Er content distributions within the ROX fuel assembly were considered. In addition, the Er content distribution was also considered in the axial direction of the ROX fuel pin. With these modifications, a power peaking factor even lower than the one in a conventional UO 2 fueled core can be obtained. The RIA and LOCA analyses of the modified core have also shown the comparable transient behaviors of ROX partial loading core to those of the UO 2 core.

Guided Wave Tuning Principles for Defect Detection in Tubing

Dispersion diagrams for longitudinal modes and several flexural modes are given. A partial loading oblique incidence technique was introduced for non-axisymmetric guided wave generation. Acoustic fields for partially loaded generation of guided waves were obtained along a sample Inconel steam generator tube surface. The axial field and the circumferential fields were non uniform. Even though the acoustic field was much more complicated than in the case of axisymmetric modes, the study of non-axisymmetric mode cannot be avoided; excitation of a single symmetric mode is often difficult due to limited access and transducer efficiency and there is also mode conversion after scattering from defects. For 100% inspection coverage of tubing and piping, three dimensional tuning (distance, frequency, and incident angle tuning), was employed. A single combination of incident angle, position, and frequency may miss defects in “blind spots”. However, complete inspection coverage of a whole cross sectional area over a certain distance of tubing was successfully demonstrated through a multi crack detection experiment by using the three dimensional tuning concepts. Also, the use of non-axisymmetric guided waves for a large distance inspection capability was successfully demonstrated.