Shock Protection Research Articles

Thermal shock protection with scalable heat-absorbing aerogels

Improving thermal insulation is vital for addressing thermal protection and energy efficiency challenges. Though silica aerogel has a record-low thermal conductivity at ambient pressure, its high production cost, due to its nanoscale porous structure, has hindered its widespread use. In this study, we introduce a cost-effective and mild method that enhances insulation by incorporating phase change materials (PCMs) into a micron-porous framework. With a thermal conductivity at 0.041 W m−1K−1 on par with conventional insulation materials, this PCMs aerogel presents additional advantages for thermal protection from transient high-temperature loads by effectively delaying heat propagation through heat absorption. Moreover, the PCMs aerogel remains stable under cyclic deformation and heating up to 300 °C and is self-extinguishing in the presence of fire. Our approach offers a promising alternative for affordable insulation materials with potential wide applications in thermal protection and energy conservation areas.

Testing the shock protection performance of Type I construction helmets using impactors of different masses.

Wearing protective helmets is an important prevention strategy to reduce work-related traumatic brain injuries. The existing standardized testing systems are used for quality control and do not provide a quantitative measure of the helmet performance. To analyze the failure characterizations of Type I industrial helmets and develop a generalized approach to quantify the shock absorption performance of Type I industrial helmets based on the existing standardized setups. A representative basic Type I construction helmet model was selected for the study. Top impact tests were performed on the helmets at different drop heights using two different impactor masses (3.6 and 5.0 kg). When the helmets were impacted with potential impact energies smaller than the critical potential impact energy values, there was a consistent relationship between the peak impact force and the potential impact energy. When the helmets were impacted under potential impact energies greater than the critical potential impact energy values, the peak impact forces increased steeply with increasing potential impact energy. A concept of safety margin for construction helmets based on potential impact energy was introduced to quantify the helmets' shock absorption performance. The proposed method will help helmet manufacturers improve their product quality.

Development of porous hydroxyapatite/PVA/gelatin/alginate hybrid flexible scaffolds with improved mechanical properties for bone tissue engineering

Porous scaffolds based on gelatin and hydroxyapatite particles (HAp) are promising for applications in bone tissue engineering and regenerative medicine. However, they are not ideal for stress and shock protection due to low compressive strength, brittleness, and poor toughness. Herein, we developed porous hybrid scaffolds by combining multiple components into a single bone scaffold, including hydroxyapatite nanoparticles (HAp NPs), alginate, polyvinyl alcohol (PVA), and gelatin with different gelatin/PVA composition ratios. HAp NPs were synthesized in situ in PVA solution and scaffolds were fabricated using a freeze-drying method. The results showed good physicochemical properties of the scaffolds: formation of pure HAp NPs phase, high porosity, large pore sizes, large swelling capacity depending on varying gelatin/PVA ratios, as well as a long-term degradation rate up to 28 days. The porous scaffolds exhibited compressive strength close to the cancellous bone with stress-strain behavior exhibiting three-stage flexible behavior indicating improved fracture resistance with an energy absorbing capability up to 1.9 MJ/m3. The scaffolds have a yield strength of 70–403 kPa, a compressive strength at 65 % strain of 0.96–1.80 MPa, a nonporous elastic modulus of 10.44–12.40 GPa, and a densification strain of approximately 0.92 %. This work develops three-dimensional (3D) porous hybrid bone scaffolds with mechanical strength within the minimum compressive strength of cancellous bone and mechanical energy absorption capacity favor for cancellous bone repair, bone tissue engineering, and regenerative medicine applications.

Facial Recognition and Shock Protection: A Comprehensive Anti-Theft System for Vehicles

Vehicle Anti-Theft Detection and Protection with Shock employs a robust security system integrating facial recognition technology and shock protection mechanisms. A camera, connected to a Python-installed PC, facilitates facial recognition to identify authorized users. In the event of an unrecognized face, the system triggers an immediate response by sending an alert email to the registered user. This aspect adds an extra layer of security to deter potential thefts. In addition to the facial recognition feature, the project incorporates a shock protection mechanism inspired by a mosquito bat. This innovative approach involves integrating a shock mechanism that can be activated remotely. If unauthorized access or tampering is detected, the shock mechanism provides an additional deterrent, enhancing the security of the vehicle. The combination of facial recognition and shock protection contributes to a comprehensive anti-theft system, ensuring both user authentication and a swift response to potential threat Keywords : Arduino, Python installed PC, Vehicle security, Relay, Inverter

Investigation of heat and mass transfer of oldroyd – 8 constant fluid in wire coating process employing response surface methodology

Wire coating is widely used for electrical insulation, shock protection, preventing leakage, and facilitating smooth current flow. This study aims to evaluate the applicability of Oldroyd-8 constant fluid for wire applications in a magnetic field using a pressure-type die. Based on the Buongiorno model with a constant pressure gradient and temperature-dependent thermophysical properties, governing equations are developed. These equations are transformed into dimensionless form and solved numerically. The study thoroughly investigates key features, including momentum, thermal distribution, nanoparticle volume fraction, and shear stress rate. Also, this study employs Response Surface Methodology to optimize heat transfer and shear stress rates in coated wire. Quadratic models, developed through a central-composite design, determine optimal levels for the Oldroyd-8 constant fluid parameter and nanofluid parameters, ensuring optimal heat transfer and shear stress rates for the melt. Nanofluid parameters contribute to an improvement in the thermal distribution profile. Optimal heat transfer and shear stress rate occur when the nanofluid parameters are minimized, and non – Newtonian fluid parameter is maximized.

Emerging and legacy contaminants on the Brazilian southern coast (Santa Catarina): A multi-biomarker approach in oysters Crassostrea gasar (Adanson, 1757)

Coastal environments, such as those in the Santa Catarina State (SC, Brazil), are considered the primary receptors of anthropogenic pollutants. In this study, our objective was to evaluate the levels of emerging contaminants (ECs) and persistent organic pollutants (POPs) in indigenous Crassostrea gasar oysters from different regions of SC coast in the summer season (March 2022). Field collections were conducted in the São Francisco do Sul, Itajaí, Florianópolis and Laguna coastal zones. We analyzed the bioaccumulation levels of 75 compounds, including antibiotics (AB), endocrine disruptors (ED), non-steroidal anti-inflammatory drugs (NSAIDs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and pesticides. Furthermore, we assessed biomarker responses related to biotransformation, antioxidant defense, heat shock protection and oxidative damage in oysters' gills. Prevalence of ECs was observed in the central and southern regions, while the highest concentrations of POPs were detected in the central-northern regions of SC. Oysters exhibited an induction in biotransformation systems (cyp2au1 and cyp356a1, sult and GST activity) and antioxidant enzymes activities (SOD, CAT and GPx). Higher susceptibility to lipid peroxidation was observed in the animals from Florianópolis compared to other regions. Correlation analyses indicated possible associations between contaminants and environmental variables in the biomarker responses, serving as a warning related to climate change. Our results highlight the influence of anthropogenic activities on SC, serving as baseline of ECs and POPs levels in the coastal areas of Santa Catarina, indicating more critical zones for extensive monitoring, aiming to conserve coastal regions.

Health and safety in hair salons during the Covid-19 situation: A cross-sectional study in a semi-urban district in Thailand

ObjectiveSince the COVID-19 crisis in Thailand, the need for salons to have impeccable hygiene and client-hairdresser monitoring heightened. Due to scarce research on the COVID-19 preventive measures taken by hairdressing salons in semi-urban locations in Thailand during the pandemic, this study aimed to evaluate the standard of hair salons in preventing COVID-19 disease transmission in a semi-urban district in the northeastern region of Thailand. MethodsUsing the purposive sampling method, data were collected from 22 Hair Salons. Data collection tools were a self-completed questionnaire designed into different sections to obtain information on demographics, work conditions and environmental health standard compliance according to guidelines set by the Thai Ministry of Public Health during the COVID-19 pandemic. Descriptive analyses were done, such as mean, standard deviation, and frequency. ResultsThe mean age of our respondents was 41.82 (±8.18) years, more than half were females (63.6 %). Most of the criteria assessing beauty salon standards according to Department of Health guidelines were passed, with all of the salons passing the lighting evaluation and mostly passing the heat and electric shock protection system evaluation, but the implementation of guidelines for preventive measures during the COVID-19 epidemic, according to Department of Health guidelines, suggested non-compliance by most hair Salons. ConclusionBeauty salons should implement and strictly adhere to guidelines according to Department of Health standards. Training or education sessions regarding the prevention of infectious disease transmission should be conducted, as hairdressers should be motivated to comply with health and environmental health standards for both salon staff and clients' confidence. Further research should also be done on the behaviours associated with health risks in beauty salons at the national or border-nation level.

A novel polar mechanical metamaterial with dual deformation characteristics

Polarity refers to the phenomenon of an object exhibiting opposite intrinsic properties in opposing directions, which plays a fundamental role in various fields including mechanical diodes, mechanical logic gates, and shock protection. This paper proposes a new mechanical metamaterial with polar and dual deformation characteristics based on a fishbone-like structure to enable a given surface structure to be hard while its opposite side is soft, while also enabling the task of adapting to different load levels on the soft side. The mechanical metamaterial displays double-stress platforms and exhibits a significant difference in mechanical response when loaded on opposite sides. Through numerical simulations, the polarity characteristic spectrum of the mechanical metamaterial is identified. The stress platform with a soft boundary predicted using Euler's instability theory was verified through both numerical simulation and experimentation. The dimensionless parameters for load differences are defined to evaluate the polar characteristics of polar mechanical metamaterials, and design guidelines are provided for achieving significant polar characteristics of polar mechanical metamaterials by discussing the influence of geometrical parameters. The proposed polar mechanical metamaterial introduces a novel design concept applicable to signal transmission, isolation, and energy absorption for different load levels.

In-situ formation of the BSG bubbles toward SiC/SiC composites protection mechanisms under thermal shock treatment

The thermal shock protection of SiC/SiC composites have become pivotal challenges in promoting their application in a heat field environment. This study presents a borosilicate glass (BSG) coating was fabricated successively by slurry brushing-sintering for SiC/SiC composites. The results show that the coated SiC/SiC composites exhibit excellent thermal protective resistance with a rather light mass change (<0.59%) at 1200 °C (ΔT = 1000 °C) for 750 cycles. All tested samples possess a high residual strength of more than 95.71% retention. Moreover, the protection mechanisms of the coated SiC/SiC composites are analyzed that the relevance involves the BSG bubbles in-situ formation and dynamic filling. The bubbles are possibly due to generation and pressure of CO and CO2 at the SiC-BSG interface during the rapid heating and cooling. The oxidation kinetics is controlled by diffusional mechanisms, and the growth rate constant and kinetic exponent were 0.23 and 0.37 for the BSG@SiC/SiC composites. The internal structure was not oxidized, indicating that the BSG coating has excellent protection.

Dependence of the kinetic energy absorption capacity of bistable mechanical metamaterials on impactor mass and velocity

Using an alternative mechanism to dissipation or scattering, bistable structures and mechanical metamaterials have shown promise for mitigating the detrimental effects of impact by reversibly locking energy into strained material. Herein, we extend prior works on impact absorption via bistable metamaterials to computationally explore the dependence of kinetic energy transmission on the velocity and mass of the impactor, with strain rates exceeding 102 s−1. We observe a large dependence on both impactor parameters, ranging from significantly better to worse performance than a comparative linear material. We then correlate the variability in performance to solitary wave formation in the system and give analytical estimates of idealized energy absorption capacity under dynamic loading. In addition, we find a significant dependence on damping accompanied by a qualitative difference in solitary wave propagation within the system. The complex dynamics revealed in this study offer potential future guidance for the application of bistable metamaterials to applications including human and engineered system shock and impact protection devices.

A Review Paper on Designing of Knee Support System for Elderly People

Knee pain can now occur in people as young as their 30s, not just in their 60s and 70s. As the elderly population grows, hospitals will have a hard time accepting more patients due to the high demand for services. The focus will shift from post-accident care to preventative care, especially for people with knee pain. The first step in designing and developing a successful knee exoskeleton is to conduct high-quality research on the following topics: knee structure, the diseased state of osteoarthritis, knee kinematics, gait analysis, the existing market for knee exoskeletons, actuation methods, novel software, sensors, and more. The study found that applying heat to the knee increases tissue temperature, softens surrounding tissues, reduces tissue viscosity, increases connective tissue extensibility, reduces pain, and increases joint mobility. Flexible sensors are used in wearable devices such as electric skin, flexible strain gauge sensors, motion detectors, and self-repairing sensors. A self-adjusting knee joint is being developed to allow passive self-alignment with the ICR of the natural knee. Neoprene rubber is a synthetic closed-cell rubber used in medical devices, but it lacks breathability and restricts the movement of water vapor, moisture, and heat. Knitted stretch fabrics provide warmth and compression to injured areas, and foam provides shock protection and pressure points to promote healing. Test methods are used to evaluate the dimensional, mechanical, and thermo-physiological properties for material selection. A wearable suit design was studied using a Design of Experiments approach, with eight key parameters identified and an optimization method developed. Robotics and automation technology were used to address discomfort issues in the body-worn knee exoskeleton design.

Experimental Study on the Transient Electric Shock Characteristics Between Metal Sheds and the Human Body Near Ultrahigh Voltage Alternating Current Transmission Lines

With the development of ultrahigh voltage (UHV) transmission lines in China, line corridors are becoming increasingly limited, and the lines pass closer to inhabited areas and the occurrence probability of induced electric shocks are increased. The research on transient electric shock and human sensory is essential due to the displeasure and complaints of people on electric shock. In this article, a real-size metal shed was established near a 1000-kV UHV alternating current (ac) transmission line, and the induced voltage and transient current characteristics were studied when the human body was in contact with the shed. Then, the amplitude and pulsewidth of the transient electric shock current were investigated, and the associations between discharge energy and sensation were established. The research found that transient electric shock is the most serious when the grounded human body contacts the insulated shed, and the imparted electric shock energy reaches 25 mJ. When the body and the shed are grounded, there is no electric shock sensation. When the insulated human body is in contact with the insulated shed, the electric shock sensation is intermediate, and women's perceptions of pain are more intense. The results provide references to transient electric shock protection for power transmission lines.

Biomechanical effects of a hard insert and air space in mouthguards on the shock absorption and protection against fractures of direct resin composite veneers from trauma.

Mouthguards (MTG) are used to prevent dental trauma. However, their protective effect on esthetic restorations and whether modified MTGs are beneficial is uncertain. The aim of this study was to evaluate the effect of hard inserts and air spaces in MTGs in protecting direct resin composite veneers during impact. Twenty resin composite veneers (1.0 mm) were prepared on upper right central incisors on printed maxilla models using polyether. The effect of the MTGs was evaluated in four groups (n = 5): Con-MTG, conventional custom-fit MTGs made with two layers of ethylene vinyl acetate (EVA); Air-MTG, MTGs with the insertion of 2.0 mm air space between the two layers of EVA and tooth surface; PETG-MTG, MTGs with 1.0 mm of polyethylene terephthalate glycol-modified (PETG) inserted between the EVA layers; and No-MTG, comprising resin composite veneers without MTG. The printed models were fixed in a pendulum device, and the impact was performed at 30°. The strain (μS) and shock absorption (%) of the MTG were recorded using strain gauges. Failure modes and cracks were evaluated using macro photography and transillumination and analyzed using the chi-square test. Strain and shock absorption data were analyzed using the one-way analysis of variance followed by Tukey's test (α = 0.05). Mouthguards reduced strain and enhanced shock absorption, regardless of the MTG type (p < .001). Con-MTG, Air-MTG, and PETG-MTG had shock absorption rates of 76.1%, 72.3%, and 33.4%, respectively (p < .001). The single No-MTG model had a root fracture, while all the others had superficial damage. None of the MTG models had cracks or fractures. Mouthguards protected the resin composite veneers. The Con-MTG and Air-MTG groups had lower strain and greater shock absorption than the PETG-MTG. Resin veneers had no cracks or damage following MTG use. However, 80% of the veneers had surface damage when no MTG was used.

მრავალსაფეხურიანი სადაწნეო ჰიდროსატრანსპორტო სისტემების ჰიდრავლიკური დარტყმებისაგან დამცავი მოწყობილობა

Pipeline hydrotransport systems began to develop rapidly from the second half of the last century. This was especially the case in the mining and mineral industries, when it was used for hydraulic transportation of loose solid materials. One of the fragments of the fundamental works performed by the author at G. Tsulukidze Mining Institute – the construction performance and working principle of the hydraulic shock protection device of multistage pressure hydraulic transport systems – is reviewed. The construction includes a pneumohydraulic accumulator, the body of which is connected to the suction pipe of the pumping unit through a tube on which a foot is mounted, and the bottom is connected to the necessary pipeline with a transfer pipe. Additionally, reverse valves are installed on the supply pipe and the transfer pipe.

KEC 기준을 적용한 저압 전기설비의 접지저항값에 따른 접지계통 안전성 분석

The KEC(Korea Electro-technical Code) is applied in accordance with the international standard conformity requirement for installation and inspection of domestic electrical equipments. The main differences between KEC and the past standard are classification of grounding methods according to the type of grounding system, and protection against electric shock. Accordingly, in the standard of human body protection from electric shock, the allowable dangerous voltage has become more important than the grounding resistance value, but in the case of design and construction of low voltage electrical equipment, it is difficult to calculate that. Therefore, in this paper we model the types of grounding systems that can be applied in Korea through simulation, and the safety of the grounding system according to the grounding resistance value in terms of electric shock protection is reviewed by simulating human electric shock case study.

Development of adaptive granular metamaterials for impact mitigation

Granular crystals exhibit highly nonlinear impulse responses and are therefore excellent candidate materials for applications such as vibration absorption, impact mitigation, and shock protection. This work presents a new class of adaptive metamaterials in the form of granular crystals immersed in MR fluids which offer the unique ability to reversibly generate rheological defects at any spatial location using external magnetic fields. To demonstrate the utility and efficacy of these tunable metamaterials, a novel experimental methodology was developed to visualize the wave propagation through granular crystals immersed in opaque fluids subjected to low-speed impact loading. This experimental approach relied on a drop-tower-based setup to subject the granular crystals immersed in MR fluids to low-speed impact loading. The kinematic and strain fields in each grain at any instant during impact loading were calculated using a combination of high-speed imaging and digital image correlation. The experimental methodology was employed to illustrate the influence of “point” defects generated by using an external magnetic field on the wave propagation in granular immersed granular crystals. In this letter, a single rheological “point” defect was introduced in the center of the granular crystals using external magnetic fields of varying magnitudes, and the influence of the strength of the magnetic field on the wave dynamics was quantified. The experimental measurements demonstrated that the strength of the magnetic field has a significant influence on the wave propagation process, and it is possible to control the spatial kinetic and strain energy distribution by varying the magnetic field.

Regulation Mechanism of the Shock Waves in a Pentamode Lattice-Ring Structure Subjected to Collision

This paper hopes to explore the application potential of pentamode materials in the field of shock protection. Hammer percussion tests revealed that the peak strain of the inner-ring front shock surface of the pentamode lattice-ring structure is 103.9% of that of the inner-ring rear shock surface. According to the simulation results, for a solid ring of equal mass made of the same base material, the ratio mentioned above reaches 3385.7%. Compared with the solid ring of equal mass made of the same base material, the pentamode lattice-ring structure saw a decline of 65.5% in the peak strain of its inner-ring front shock surface. The distribution laws of the group velocity characterizing energy-flow characteristics were discovered by calculating cell dispersion curves in various layers of the pentamode lattice-ring structure. The laws governing the effects of cellular structure parameters on group velocity anisotropy and pentamode characteristic parameters were also revealed. It was found that the deflection angle of the energy-flow vector is positively correlated with group velocity anisotropy and that the effects of pentamode characteristic parameters π and μ on the deflection angle of the energy-flow vector vary greatly in different value ranges. The deflection angle of the energy-flow vector has a decisive effect on the protection performance of the pentamode lattice-ring structure. The conclusions of this study can provide some theoretical support for the shock protection of submarine structures.

A detection method for biological electric shock based on improved sample entropy

Biological electric shock detection is the key to safeguarding of persons in grids. However, present methods cannot make protectors trip correctly by extracting the characteristics of living things. To improve the situation, this paper presents an innovation by which the protectors can be adaptive to trip correctly when the biological electric shock happens. The basic principle of proposed method is extracting biological electric shock characteristics (BESC) from measured current based on the sample entropy (SampEn). It can distinguish whether the electric shock is caused by mammals or not. Besides, for practical need, a fast BESC calculation method is proposed in order to reduce redundant computation. Moreover, an execution module for electric shock protection based on DSP is developed. And electric shock experiments have been carried out to validate the effectiveness of proposed method. The results show that accuracy of biological electric shock detection is improved and proposed method is practical even in strong noise environment.

Aspects of the earthing and short-circuit device’s safety quality

Earthing and short-circuit devices are part of the category of equipment and means of electric shock protection, and their purpose is to protect workers in the event of an accidental voltage in the work area while doing electrical installation work. The purpose of this study is to convey the findings of research into the level of safety that these devices must provide, not only in terms of electrodynamic and electro thermal consequences that occur during a short-circuit, but also in terms of mechanical, chemical, and environmental aspects. The study's risk analysis of safety performance provides critical information for earthing and shortcircuiting device manufacturers to ensure the safety function throughout their use, as well as for workers to pick, use, and maintain.

MARKETING SUPPORT FOR THE PROCESS OF STUDYING CONSUMER PREFERENCES ON THE HEATING APPLIANCES MARKET

The article is devoted to the problems of marketing support for the process of studying consumer preferences on the market. It is proved that the study of consumer preferences involves the development of a system of marketing research of commodity markets and the determination which products the consumer prefers, the level of satisfaction with the product assortment on the market, how he chooses the place of purchase of the product, when he decides to buy the product, how the decision to re-purchase is made, on which characteristics he chooses the place and time of purchase of the product and so forth. It has been proven that the issue of ensuring the stability of relations with consumers (frequency of consumption, volume, ways, who is consumed), understanding the sensitivity of consumers to competitors’ brands require more detailed study. The purpose of the study is to develop a sequence of research of consumer preferences on the market of heating appliances on the basis of determining the frequency of consumption, modes of consumption, understanding the sensitivity of consumers to competitors’ brands. The study has demonstrated that in choosing an electric heater, buyers pay more attention to its technical characteristics and prefer to consult at the place of purchase. However, a significant number of users still choose online shopping, which means that enterprises should choose intermediaries which can sell in physical stores as well as online (online shopping is especially in demand in the period of the pandemic). One of the selection criteria for users of electric heaters has become the presence of additional auxiliary functions, such as shock protection, frost protection, protection against burns, child lock, thermostat, remote control, timer and warranty service. Enterprises need to improve their production, because this type of product is bought for long-term use, and therefore must meet all safety standards and be easy to use. The market of electric heaters in Ukraine is quite saturated with various brands, but not sufficiently developed in terms of advertising activities. In order to improve their market position, producers of electric heating appliances need to increase their advertising activity through various communication channels and media.