Back Configuration Research Articles

Seismic Response of RCC Buildings on Hill Slopes with Step Back and Step Back - Set Back Configuration

Framed structures constructed on hill slopes have different structural behavior than those on flat ground due to the scarcity of flat land. As these buildings are unsymmetrical, they attract large amounts of shear forces and torsional moments, leading to unequal distribution due to varying column lengths. In this study, the dynamic response of hill buildings has been compared with step back and step back set back building without and with bracing at corner of the building in terms of maximum storey stiffness and storey displacement. Two different types of buildings have been modeled and analyzed using ETABS v 18.0 finite element code. A parametric study has been conducted, in which hill buildings are geometrically varied in height of the structure due to hill slope. All sixteen analytical models have been subjected to seismic forces along and across the hill slope direction and analyzed by using the Response Spectrum Method.
 All 16 models were analysed using ETABS v18. Three dimensional space frame analysis is carried out for four different configurations such as step back buildings with bracings at corner of the building, step back buildings without bracings, step back and set back building with bracings at corner of the building, step back and set back building without bracings. The maximum storey stiffness and storey displacement for the step back and step back-setback buildings with and without bracing are at 15 ͦ and 30 ͦ, respectively, compare with bracing buildings, the value in step back & step back set back building drastically decreases, resulting in the stability of the building.

Numerical investigation on dynamic damage behavior of a novel N-shaped perforated armor plate under ballistic impact

Armor steel is widely used for ballistic resistance in military infrastructures and vehicles. However, the high areal density of monolithic steel plates presents challenges in balancing protection and maneuverability. This study focuses on a novel armor design, invented by the authors: An N-shaped perforated armor plate (NPAP). The NPAP consists of a perforated plate, an inclined plate, and a back plate. A validated finite element (FE) model was used to analyze the dynamic damage behavior of the NPAP target and projectile under ballistic impact. Numerical simulation revealed that the NPAP target combined the edge and obliquity effects, resulting in asymmetric interaction and causing yaw and fracture of the projectile. The kinetic energy of the steel core after penetrating the NPAP target decreased by 84.7–88.0% compared to the initial kinetic energy. The NPAP target showed a 20.7–43.9% lower residual depth of penetration (RDOP) compared to the monolithic target. Furthermore, the effects of the dip angle of the inclined plate and plate thickness configurations on the ballistic performance of NPAP were examined. The results indicated that the NPAP target’s ballistic performance is more susceptible to the impact location on the perforated plate with a larger dip angle of the inclined plate. Additionally, the NPAP target with a thin perforated plate and a thick back plate configuration exhibited better ballistic performance, given the constant thickness of the inclined plate.

Exergy analysis of pressure reduction, back pressure and intermittent air supply configuration of utilization/expansion stage in compressed air systems

Despite their many advantages, industrial compressed air systems are characterized by high energy consumption and very low energy efficiency. This is primarily due to the oversizing of pneumatic actuators, leading to excessive compressed air consumption in the utilization stage. Various methods have been proposed in the literature to address this issue, which can be classified into three groups: supply pressure reduction, back pressure increase, and intermittent power supply. However, no exergy analysis compares these methods in the utilization stage of a pneumatic system was performed. In this study, we conducted an exergy analysis to compare the exergy consumption and exergy savings of different pneumatic system configurations: the classic configuration, supply pressure reduction, back pressure increase, and intermittent power supply. The paper shows the most key places in CAS in terms of exergy losses, which result mainly from dead volumes, outlet loss and oversizing of components such as directional control valve, distributed pneumatic line and actuator. Losses in those components can amount to over 80% of input exergy and can be reduced even 3–9 times. Exergy evaluation of oversizing configurations showed that the highest exergy savings were obtained for a back pressure configuration (77%) and intermittent air supply (75%). The exergy savings for the pressure reduction configurations amounted to almost 50%. The paper presents mathematical models for several individual pneumatic components, including the actuator, directional control valve, muffler, pneumatic line and pressure reducer. The demonstrated mathematical model and exergy analysis can play a instrumental role in evaluating the exergy efficiency and optimization of a pneumatic system.

Seismic Behaviors of RC Buildings in Slopping Ground

This thesis is the study of seismic behavior of RC building in hilly areas i.e. sloping grounds. The study of dynamic response of structure on hilly areas has been done. Almost 13 configuration of structure has been considered for analysis. Six of them are step-back and which consider ground slope. Six are set-back configuration which is like in plain land. Remaining one is plan buildings. Three models are normal step back, setback and plan buildings and remaining are combination of shear wall, steel bracings. Various literature reviews of studies on the seismic behavior of RC building on hilly areas i.e. sloping ground has been studied and presented in this thesis. All considered configuration of building is modeled using ETABS v20.0.0 and IS 1893:2016 and analyzed by using equivalent static analysis and response spectrum methods. Then considered buildings have been compared in terms of base shear, Fundamental time period, top storey displacement, drift and story stiffness. The seismic behavior of building on hilly areas (sloping ground) is found differ from building plain ground. Most of studies lead to conclusion that building on hilly areas (sloping ground) has higher displacement and base shear compared to building on plain land. Also conclude shorter column attracts more forces and cause damage when earthquake occurs. Step back configuration could prove more vulnerable to seismic activities. We also concluded that building with shear wall improves seismic behavior of building by increasing strength and stiffness and also reduce in deflection. Keywords: Hilly areas, step-back configuration, step-back, set- back configuration,

Acute Effects of Varied Back Squat Activation Protocols on Muscle-Tendon Stiffness and Jumping Performance.

Krzysztofik, M, Wilk, M, Pisz, A, Kolinger, D, Tsoukos, A, Zając, A, Stastny, P, and Bogdanis, GC. Acute effects of varied back squat activation protocols on muscle-tendon stiffness and jumping performance. J Strength Cond Res 37(7): 1419-1427, 2023-Intensity, movement velocity, and volume are the principal factors to successfully use postactivation performance enhancement. Therefore, 15 resistance-trained volleyball players completed 3 different back squat configurations as a conditioning activity (CA) in randomized order: (a) 3 sets of 3 repetitions at 85% 1RM (HL); (b) a single set of back squats at 60% 1RM until 10% mean velocity loss (VB); (c) and 2 sets of back squats at 60% 1RM until 10% mean velocity loss (2VB) on subsequent countermovement jump performance, Achilles tendon, and vastus lateralis stiffness with concomitant front thigh skin surface temperature assessment. The measurements were performed 5 minutes before the CA and at 2, 4, 6, 8, and 10 minutes. The jump height was significantly increased in the second minute and at peak, post-CA compared with baseline for all conditions ( p = 0.049; ES = 0.23 and p < 0.001; ES = 0.37). Skin surface temperature was significantly increased for all post-CA time points compared with baseline in the 2VB condition ( p from <0.001-0.023; ES = 0.39-1.04) and in the fourth minute and at peak post-CA in HL condition ( p = 0.023; ES = 0.69 and p = 0.04; ES = 0.46), whereas for the VB condition, a significant decrease in peak post-CA was found ( p = 0.004; ES = -0.54). Achilles tendon stiffness was significantly decreased for second, fourth, eighth, 10th, and peak post-CA in comparison to baseline for all conditions ( p from p = 0.004-0.038; ES = -0.47 to -0.69). Vastus lateralis stiffness was significantly decreased for peak post-CA compared with baseline for all conditions ( p = 0.017; ES = -0.42). We recommend using a single set of barbell squats with a 10% velocity loss as a mechanism of fatigue control to acutely improve jump height performance and avoid unnecessary increases in training volume.

The impact of rotor configurations on hemodynamic features, hemocompatibility and dynamic balance of the centrifugal blood pump: A numerical study.

To investigate the effect of rotor design configuration on hemodynamic features, hemocompatibility and dynamic balance of blood pumps. Computational fluid dynamics was employed to investigate the effects of rotor type (closed impeller, semi-open impeller), clearance height and back vanes on blood pump performance. In particular, the Eulerian hemolysis model based on a power-law function and the Lagrangian thrombus model with integrated stress accumulation and residence time were applied to evaluate the hemocompatibility of the blood pump. This study shows that compared to the closed impeller, the semi-open impeller can improve hemolysis at a slight sacrifice in head pressure, but increase the risk of thrombogenic potential and disrupt rotor dynamic balance. For the semi-open impeller, the pressure head, hemolysis, and axial thrust of the blood pump decrease with increasing front clearance, and the risk of thrombosis increases first and then decreases with increasing front clearance. Variations in back clearance have little effect on pressure head, but larger on back clearance, worsens hemolysis, thrombogenic potential and rotor dynamic balance. The employment of back vanes has little effect on the pressure head. All back vanes configurations have an increased risk of hemolysis in the blood pump but are beneficial for the improvement of the rotor dynamic balance of the blood pump. Reasonable back vanes configuration (higher height, wider width, longer length and more number) decreases the flow separation, increases the velocity of blood in the back clearance, and reduces the risk of blood pooling and thrombosis. It was also found that hemolysis index (HI) was highly negatively correlated with pressure difference between the top and back clearances (r=-.87), and thrombogenic potential was positively correlated with pressure difference between the top and back clearances (r=.71). This study found that rotor type, clearance height, and back vanes significantly affect the hydraulic performance, hemocompatibility and rotor dynamic balance of centrifugal blood pumps through secondary flow. These parameters should be carefully selected when designing and optimizing centrifugal blood pumps for improving the blood pump clinical outcomes.

Photopyroelectric spectroscopy and calorimetry

In this Tutorial, we present an overview of the development of the photopyroelectric (PPE) technique from its beginning in 1984 to the present day. The Tutorial is organized into five sections, which explore both theoretical and experimental aspects of PPE detection as well as some important spectroscopic and calorimetric applications. In the “Introduction” section, we present the fundamental basics of photothermal phenomena and the state-of-the-art of photopyroelectric technique. In the “Theoretical aspects” section, we describe some specific cases of experimental interest, with examples in both back and front detection configurations. Several mathematical expressions for the PPE signal in specific detection modes (combined back–front configurations and PPE–thermography methods) are also deduced. The “Instrumentation and experiment” section contains two subsections. The first describes several examples of setups used for both room temperature and temperature-controlled experiments. The second subsection is dedicated to the configuration of detection cells and to the various sensor/sample assemblies that are currently used in spectroscopic and calorimetric experiments for both liquid and solid samples. The “Applications” section is in fact a collection of experimental results dedicated to the thermal characterization of a wide range of solid and liquid samples. At the end of this section, we present some examples that have been selected to convey that the PPE technique is not only useful in the investigation of optical and thermal properties of a variety of condensed matter samples, but also to study physical and chemical processes such as molecular associations, food adulteration, or phase transitions. In “Concluding remarks,” we summarize the advantages of this technique in spectroscopic and calorimetric applications.

Hybrid Organic–Inorganic Perovskite Semiconductor-Based High-Flux Neutron Detector with BN Converter

Neutrons are analyzed in various fields such as space exploration, neutron radiography, and medicine. When neutrons are employed, a neutron detector is required to control the exposure dose. However, issues such as detector radiation tolerance, response linearity, and γ-ray noise limit the development of effective neutron detectors. Metal halide perovskite based direct conversion radiation detectors exhibit attractive characteristics such as being solution-processable at low temperatures and possessing tunable band gaps, low trap density, high charge carrier mobility, high radiation tolerance, and fast responses. The perovskite device’s potential for high-flux neutron applications has not been greatly determined; however, only related research has been conducted thus far. Here, we demonstrate a hybrid organic–inorganic perovskite semiconductor based neutron detector that satisfies all high-flux neutron detection requirements. The perovskite device was designed to possess a structure similar to that of solar cells and could be driven solely by the built-in potential, without an applied voltage. Using this perovskite device, a neutron detector was designed to maximize the efficiency of the back side conversion configuration and minimize sensitivity variations. Experiments on irradiation with the spectrum neutrons and calculations of the reaction rates revealed a 25 meV neutron sensitivity of 6.0 × 10–17 A n–1 cm–2 and a detection limit of 106 n cm–2 s–1. Further, an optical response test showed that a dynamic detection range with 6–7 orders of magnitude was realized. The detection characteristics for high-flux neutrons indicated a stable operation with no degradation during neutron irradiation at a fluence of −1012 cm–2. Moreover, noise from γ-rays had an insignificant effect on the accuracy of the neutron flux measurements. These results highlight that the proposed neutron detector based on a perovskite solar cell is a suitable monitoring sensor for high-flux neutrons.

Sputter-deposited CdMgTe for rear contact to CdSeTe/CdTe solar cells

CdTe-based photovoltaic device performance improvement is predominantly limited by open-circuit voltage. This work approaches the voltage deficit challenge through the incorporation of a cadmium magnesium telluride (CdMgTe) electron reflector layer at the back of 1.5- μm CdSeTe/CdTe absorbers to reduce back-surface recombination through a conduction band offset. A sputtered CdMgTe electron reflector layer permitted low fabrication temperatures and circumvented the intolerance of CdMgTe to thermal processing present in traditional close-space sublimation (CSS)-deposited CdMgTe devices. We demonstrate that sputtered CdMgTe simultaneously promotes the retention of chlorine passivation and magnesium which is not feasible with CSS fabrication. We also show the importance of the Cu and Te back contact order in CdMgTe devices. Through the optimization of the sputtered CdMgTe substrate temperature, doping, and back structure configuration, 1.5 μm CdSeTe/CdTe devices with a sputtered CdMgTe layer achieved an efficiency of 16.0%, significantly higher than with CSS CdMgTe, and demonstrated partial enactment of electron-reflector behavior. • Sputtered CdMgTe electron reflector solar cells achieve higher efficiencies than close-space sublimation-deposited. • Low temperatures of sputtered CdMgTe reduce magnesium diffusion and chlorine loss. • CdTe devices with CdMgTe electron reflectors require back contact optimization. • CdTe voltage improvement with CdMgTe limited by a partial negative back valence band offset.

Effects of crossflow filtration cell configuration on membrane separation performance and fouling behaviour

Configurations of crossflow filtration cells are important to determine membrane separation performance in laboratory studies. We systematically investigated the effects of crossflow filtration cell designs, including sealing approaches and back support configurations, on the determination of membrane water flux, salts rejection, and fouling behaviour. In particular, the definition of effective filtration area in the O-ring sealed cell could lead to an overestimated (defined as flow channel area) or underestimated (defined as O-ring enclosed area) membrane water flux compared to the benchmark data acquired from a silicone gasket sealed cell. In addition, it was found that the highly porous back support could yield higher water flux and salt rejection as well as better antifouling performance than that of the perforated plate support. The porous back support could significantly reduce the total resistance to water permeation thanks to the minimized average path length and increased hydraulic conductance for water transport. Moreover, the porous back support enabled better control of concentration polarization as it avoided local flux ‘hot spots’ that would occur above local perforations, and thus benefits membrane rejections. These findings provide important insights into the design of crossflow filtration cells for a more reliable and representative determination of membrane separation performance.

Reproducible and arbitrary patterning of transparent ZnO nanorod arrays for optic and biomedical device integration

Here, we report a robust method for fabricating ZnO nanorod arrays with arbitrary patterns on glass substrate for device integration applications. Photolithography patterned non-transparent Zn film is used as growth sites for ZnO nanorods in the hydrothermal reactions for facile and reproducible fabrication. Patterns including lines, dots, texts, and logos have been demonstrated and the dimension of ZnO nanorods are tunable. The semi-transparent ZnO nanorod/glass shows increased light transmission when immersed in water, which is an advantage when integrate into devices requiring optical imaging and sensing. For proof-of-concept purpose, surface-enhanced Raman scattering sensors based on Ag coated ZnO nanorods with back observation configuration are demonstrated and show high sensitivity.

A Flexible Robotics-Inspired Computational Model of Compressive Loading on the Human Spine

The use of powerful robotics tools in modeling and analysis of complex biomechanical systems has led to the development of computationally effective and scalable human models. Our early work in this regard focused on a humanoids-based rigid-body modeling of human kinodynamics to monitor instantaneous and accumulating effects of external loads on body joints. Nevertheless, despite their high-computational efficiency, the flexible nature of the spine and its characteristic were not taken into account, resulting in less accurate estimations of the spinal compressive forces. Accordingly, in this work, we propose a flexible model of the human spine mechanics for assessing compressive loading, and integrate it in our robotics-based whole-body model. Such a model can quantify the compressive force distribution along the spine and the muscles' activity for a measured back configuration and known external forces, which both contribute to increasing the ergonomic risk level. The muscles' activity predictions are validated through an experimental analysis on six human subjects. Three different tests are conducted considering different loading conditions. Results demonstrate the potential of the proposed approach in monitoring the spine compressive loading and predicting a muscles activity with an average relative error of 10% against experimental data. Minimizing the required number of sensors and the amount of computational resources, the presented approach is particularly suitable for online risk evaluation in a real working scenario.

Simultaneous thermal and optical characterization of semiconductor materials exhibiting high optical absorption by photopyroelectric spectroscopy

This work presents the results of the investigations on the thermal and optical properties of materials exhibiting high optical absorption. As test samples, some II-VI binary semiconductors were grown by using the Bridgman-Stockbarger method. The photopyroelectric (PPE) method, in two configurations (calorimetric and spectroscopic), was applied for both thermal and optical characterization of the specimens. The thermal diffusivity was obtained in the back detection configuration (BPPE) with an intensity-modulated laser as an excitation source. The same detection configuration, but with a tunable light source, provided information about the energy gap, the absorption coefficient, and the investigated sample's thermal diffusivity. The results obtained with these two methods were also compared with the data collected by conventional transmission and luminescence spectroscopies (absorption coefficient, energy gap). The main conclusion is the photopyroelectric spectroscopy (PPES) can provide in one measurement good quality information about the thermal and optical properties of the specimen.

Numerical investigation on the performance of impeller back seal configuration in a supercritical CO2 radial-inflow turbine

Radial-inflow turbine is a core component in supercritical CO2 (SCO2) Brayton cycle. The leakage from the nozzle outlet towards the impeller back brings a great challenge to the efficiency and security of the power system. In this paper, the labyrinth seal (LS) and dry gas seal (DGS) are arranged on the impeller back of a SCO2 radial-inflow turbine and the influence on the comprehensive performance is investigated. Results demonstrate that both LS and DGS configurations can significantly reduce leakage of the impeller back and DGS configuration performs better. Compared with the configuration without leakage, the power and efficiency of DGS configuration are only reduced by 0.27% and 0.35% respectively. The seal clearance and the inlet width have a greater effect on LS configuration. The thermo-mechanical seal deformation values of DGS configurations are all less than 8 μm, which verifies the feasibility. Finally, a novel combined seal configuration with both LS and DGS is proposed and excellent performance is achieved, providing a potential approach for the sealing problem of SCO2 radial-inflow turbine.

Effect of back cavity configuration on performance of elastic panel acoustic liner with grazing flow

This paper reports a comprehensive numerical study of noise mitigation performance of elastic panel liner comprising an elastic panel and a cavity beneath exposed to low Mach number grazing flow. A time-domain direct aeroacoustic simulation (DAS) seamlessly coupled with panel dynamics is adopted for its least assumptions taken on duct flow unsteadiness and acoustical behaviors so that both linear and nonlinear aeroacoustic-structural interactions of the problem can be fully explored. The numerical method is well validated with theoretical and experimental works on a liner with thick cavity reported in literature. The noise mitigation of liner with various combinations of cavity depth, panel length and cavity shape, are explored and the present numerical results show that back cavity configuration plays an important role in the liner problem. A decomposition method is applied to DAS acoustic solutions for uncovering the role of aeroacoustically induced panel vibration. The nonlinear effect due to aeroacoustic-structural interaction is found to be of secondary importance. Extensive cross spectral analyses between duct aeroacoustics and panel vibration reveal that the overall liner performance is largely determined by the liner elastic panel whose aeroacoustic and vibration responses are greatly modified by the variations of back cavity acoustics of the back cavity with different shapes. Based on these understandings a new configuration with acoustic absorption materials placed on a cavity wall is proposed. Detailed analysis of its numerical results shows that the introduction of acoustic absorption effectively relieves the cavity acoustics and modifies the panel responses in such a way that an enhanced liner mitigation performance over a broadband can be achieved.

Performance Analysis of Braced Reinforced Concrete Building in Sloped Terrain

The Buildings on the hills differs from other buildings constructed in plain terrain. Each floor of building steps back towards the hill slope and at the same time buildings may have designed with setbacks configuration also. Buildings constructed in hilly areas are more vulnerable to seismic environment. This study is on generating a 3D analytical model of multi-storey buildings analyzed using structural analysis tool ‘ETABS” to study the effect of varying height of columns due to sloping ground and the effect of bracing at different positions in a different configuration of the building during an earthquake. Seismic analysis has been done using the response spectrum method. The performance of the buildings on the sloping ground is highly vulnerable to earthquake on each storey level. Buildings resting on sloping ground with step back configuration are compared to buildings resting on the plain ground with same type load applied to each of the structure. From this study entire modelling the behaviour of normal ten storey building, step back, set-step back ten storey building is studied, it is found that the displacement and base shear value shows the performance of step back building and set-step back building. This is research also focus on effective placement of bracing with different types and in different positions. The displacement values show better performance by providing X bracing in the lateral direction.

Gust Load Alleviation of Flexible Composite Wing

Gust load due to atmospheric turbulence is mandatory to be considered in aircraft analysis as part of airworthiness requirement. This safety related issue becomes more relevant recently in relation to the global warming that induces more frequent and extreme atmospheric disturbances encountered during air transportation. A direct application of gust load on the wing structural analysis, however, is not recommended since it will result in a significant weight increase due to the overdesign of the wing structure. At this point, the gust load alleviation plays an important role to effectively utilize the wing structural flexibility without ignoring the safety issue. In the present work, a method to alleviate the wing gust load is proposed by considering different configurations of the wing planform, wing sweep angle, wing dihedral angle and composite material layers. The objective of the study is to minimize the wing root bending moment due to the gust. The gust load analysis of the Kim-Hwang’s wing model will be used and the results are compared to the literature for the validation purpose. A finite element approach is used to simulate the wing structure in combination with the doublet lattice method to model the wing aerodynamics. It is found that the wing dihedral angle plays insignificant changes to the wing root bending moment due to the gust load. The wing sweep angle, however, gives significant changes to the wing root bending moment. For the present configuration, the optimum swept back configuration with a 45° sweep angle and optimum composite lay-up showed an average decrease of the bending moment by 12% for frequency range of 0 to 100 Hz.

Guidelines for SUV Bodywork Design Focused on Aerodynamic Drag Reduction Using the Generic AeroSUV Model

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;SUV Aerodynamics has received increased attention as the stake this segments holds in the automotive market keeps growing year after year, as well as its direct impact on fuel economy. Understanding the key physics in order to accomplish both fuel efficient and aesthetic products is paramount, which indeed gave origin to a major initiative to foster collaborative aerodynamic research across academia and industry, the so-called DrivAer model. In addition to this sedan-based model, a new dedicated SUV generic model, called AeroSUV [&lt;span class="xref"&gt;1&lt;/span&gt;], has been introduced in 2019, also intended to provide a common framework for aerodynamic research for both experimental work and numerical simulation validation. The present paper provides an area of common ground for SUV bodywork design focused on aerodynamic drag reduction by investigating both Estate and Fast back configurations of the generic AeroSUV model. Modified bodywork geometries focused at the rear end as well as spoiler angles, are evaluated using OpenFOAM Delayed Detached Eddy Simulations (DDES) utilising a Design for Six Sigma (DFSS) approach, such that not only a sensitivity study of drag response is yielded, but a ranking in terms of the potential for drag savings in certain areas of the car, is produced.&lt;/div&gt;&lt;/div&gt;

Numerical and experimental investigation of impact on bilayer aluminum-rubber composite plate

Abstract This paper aims to investigate the performance of an aluminum–rubber composite plate under impact loading. The impact resistance of the plate has been evaluated using both experimental and numerical methods. The experimental tests were carried out using gas gun at velocities of 75, 101, 144 and 168 m/s. The energy absorption of composite plates has been closely examined for all samples. The effect of rubber layer positioning either on front face or on back face of the aluminum plate was also evaluated. It was found that the composite plate with rubber on front face provides higher performance to absorb the energy. In parallel to the experiment, a finite element model was created using the finite element software LS-DYNA to simulate the response of the aluminum–rubber composite plate under a high energy rate loading condition. The data obtained from finite element modeling shown a close agreement with the experimental results in terms of failure mechanism and energy absorption. In addition, a parametric study was carried out incorporating different impact velocities, rubber formulation, rubber layer thickness, interface bonding strength between rubber and aluminum layers and ballistic performance of aluminum-rubber sandwich panel. It was concluded that by increasing the rubber layer's thickness the energy absorption of the composite plate will be increased, especially when rubber layer placed in front face of the aluminum plate. Although at high interface bonding of rubber and aluminum layer, the composite with rubber layer in front face has better performance, but low bonding of interface lead to higher energy absorption in back face configuration.

Coexistence of Phases in Royal Jelly Detected by Photopyroelectric Calorimetry

Four samples of commercial royal jelly (RJ), delivered by different distributors, were characterized by photopyroelectric (PPE) calorimetry. The thermal diffusivity was obtained in the back PPE configuration by performing a sample thickness scan of the phase of the PPE signal. In order to determine the thermal effusivity, a frequency scan of the phase of the PPE signal was performed in the front PPE detection configuration. Similar values for all of the static and dynamic thermal parameters were obtained for all of the investigated samples. Additional phase transitions measurements were performed in the front PPE configuration, in the −15 °C to 5 °C temperature range. The results were divided: two samples presented only one first order solid to liquid phase transition, but other two underwent two phase transitions indicating a coexistence of two different phases that were probably free and bonded water. In conclusion, the PPE method, used in a temperature scan arrangement, offers structural information about these samples.