Pack Weight Research Articles

Frequency of Neck, Shoulder and Back pain due to Heavy Backpacks among Private School Children of Islamabad: A Descriptive Survey

School going children carry heavy back pack on daily basis. Heavy backpack can place extra pressure on shoulder, neck and back that can lead to pain in these regions of body. Objective: To explore the occurrence of neck, shoulder and back pain in school going children because of carrying heavy bag. Methods: A cross-sectional descriptive survey was conducted amongst school children of Islamabad from April 2023 to July 2023. A total of 274 school going children from various private schools of Islamabad region were the part of this study. School going children aging from 10 to 17 years of age of either gender with no history of musculoskeletal problems were included in the study. Data collection questionnaire incorporated standard Nordic Musculoskeletal disorder tool. Data were analyzed on SPSS version 25.0. Results: Children who carry back pack weight more than 10% showed more musculoskeletal symptoms in neck, shoulder and back. Results showed that frequency of musculoskeletal symptoms such as back pain was 171 (62.4%) and 97 (35.4%) students out of 100 who claimed no pain in back due to heavy backpack. In addition, the frequency of neck pain was 184 (67.2%) and 84 (30.7%) students who responded no neck pain due to heavy backpack. The frequency of shoulder pain was 86 (31.3%). Conclusions: Students with heavy back pack are more prone to develop musculoskeletal disorders including neck, shoulder and back pain.

Thermo-electrochemical level-set topology optimization of a heat exchanger for lithium-ion batteries for electric vertical take-off and landing vehicles

Developing electric vertical take-off and landing vehicles (eVTOL) that can meet the demanding power and energy requirements entails significant challenges, one of which is due to the weight of the battery packs. To address this challenge, optimization techniques can be employed to achieve lightweight designs while satisfying thermal criteria. This study focuses on optimizing a battery heat exchanger housing a high-energy-densitycylindrical cell using the level-set topology optimization method. To accurately account for heat generation from battery electrochemistry, we investigate both a high-fidelity, the Doyle Fuller Newman (DFN) model, and a low-fidelity electrochemical model, the Single Particle Model (SPM), which are compared to experimental results for an eVTOL flight profile. The novelty of the proposed approach resides in the integration of the electrochemical models within a three-dimensional unsteady thermo-electrochemical topology optimization framework. The battery heat exchanger is optimized considering the heat generated by the batteries at the material scale due to the system power requirements. The heat generated by the battery is incorporated as a source term in an unsteady heat conduction finite element model, forming the basis of the optimization process. Our objective is to minimize the integrated thermal compliance over time while satisfying a volume constraint, employing the level-set method. The SPM proves competent in predicting the voltage profile but underestimates the temperature increase. On the other hand, the DFN model accurately predicts both the temperature increase and the voltage profile, making it suitable for the thermal analysis of cells in eVTOL vehicles. Surprisingly, steady-state optimization turns out to be sufficient to generate optimized topologies that perform similarly to transient cases for the case investigated but at a reduced cost. By integrating electrochemical modeling, level-set topology optimization, and heat transfer analysis, our study contributes to the development of lightweight and thermally efficient battery heat exchangers for eVTOL vehicles, which can be extended to battery packs. Importantly, the presented methodology is versatile and can be applied to different battery chemistries, form factors, and power profiles.

Research on improving the reliability and reducing the weight of battery packs for railway vehicles

Research on improving the reliability and reducing the weight of battery packs for railway vehicles

Performance Analysis of a Wildlife Tracking CubeSat Mission Extension to Drones and Stratospheric Vehicles

This study presents a performance analysis for an Internet-of-Things wildlife radio-tracking mission using drones, satellites and stratospheric platforms for data relay with Spread Spectrum Modulation devices. The performance analysis is presented with link and data budgets, calculations of the area coverage, an estimation of the time resolution and allowable data amount of each collar, a power and energy budget and consequent battery pack and collar weight estimations, cost budgets, and considerations on synergetic approaches to incorporate more mission segments together. The paper results are detailed with example species to target with each collar weight range, and with design drivers and guidelines to implement improved mission segments.

A Review of 3D Printing Batteries

To stabilize the Earth’s climate, large-scale transition is needed to non-carbon-emitting renewable energy technologies like wind and solar energy. Although these renewable energy sources are now lower-cost than fossil fuels, their inherent intermittency makes them unable to supply a constant load without storage. To address these challenges, rechargeable electric batteries are currently the most promising option; however, their high capital costs limit current deployment velocities. To both reduce the cost as well as improve performance, 3D printing technology has emerged as a promising solution. This literature review provides state-of-the-art enhancements of battery properties with 3D printing, including efficiency, mechanical stability, energy and power density, customizability and sizing, production process efficiency, material conservation, and environmental sustainability as well as the progress in solid-state batteries. The principles, advantages, limitations, and recent advancements associated with the most common types of 3D printing are reviewed focusing on their contributions to the battery field. 3D printing battery components as well as full batteries offer design flexibility, geometric freedom, and material flexibility, reduce pack weight, minimize material waste, increase the range of applications, and have the potential to reduce costs. As 3D printing technologies become more accessible, the prospect of cost-effective production for customized batteries is extremely promising.

The oil bath thermal cycling absorption process design and separation process research

Thermal cycling absorption process (TCAP) has been developed for years to support the separation of hydrogen isotopes, which has the characteristics of high separation efficiency and high recovery rate. The design of separation column structure, heating and cooling (H&C) system and technological parameters are the basis of TCAP technical process study and are the key points of TCAP engineering research. In this work, an improved separation system has been designed and built based on an oil bath H&C system for the first time. The separation column in this facility is 45 m long and the packing weight in the column is up to 8 kg. The separation experiments were carried out based on this facility, and the process parameters were adjusted according to the size of the separation column, which proved the superior performance of this facility. The separation experiments show that for 50% D2 - 50% H2 feed gas, the deuterium abundance can reach to 99% and the steady state extraction can be realized in production mode with the processing capacity over 400 standard L per day. Another experiment has been carried out with 1% D2 - 99% H2 feed gas, and the deuterium abundance exceeded 10%, verifying the separation ability at low abundance deuterium feed gas. Furthermore, the extraction rate can reach to 25% column capacity when the deuterium abundance in production gas is 5%.

Battery Hybrid Energy Storage Systems for Full-Electric Marine Applications

The high cost of Lithium-ion battery systems is one of the biggest challenges hindering the wide adoption of electric vessels. For some marine applications, battery systems based on the current monotype topologies are significantly oversized due to variable operational profiles and long lifespan requirements. This paper deals with the battery hybrid energy storage system (HESS) for an electric harbor tug to optimize the size of the battery system. The impact of battery hybridization was investigated on three key performance indicators inclusive of cost, system efficiency, and battery weight. The design life of the battery system is considered to be 10 years, and NMC and LTO cell technologies are used as high-energy (HE) and high-power (HP) battery cells. The HESS design is based on a parallel full-active architecture with a rule-based energy management strategy. The results of this research indicate that battery hybridization can reduce the system cost by around 28% and 14% in comparison with a monotype battery with LTO and NMC cells, respectively. Although no noticeable difference in system efficiency is observed between the monotype system and HESS, battery hybridization reduces the total weight of the battery cells by more than 30% compared to monotype topology. This study implies that the hybridization of battery systems could be a promising solution to reduce the cost and weight of large battery packs in electric vessels.

Association of Backpack Loads and Wearing Time with Musculoskeletal Disorders in School Children of Wah Cant Pakistan: Correlational study

Background: Young children are carrying heavy bags to and from their schools. The use of backpacks increases recently because of several factors, including decreased availability of school lockers, increased homework, text books & other belongings being carried to school. All these factors amplify backpack weight which have drastic effects on young students’ musculoskeletal system. Methods: This was a correlational study. Data collection was done between Septembers to December 2018. The inclusion criteria were healthy young boys and girls of school children, with no known history of any musculoskeletal disorder or any other deformity or pathology. Survey was done through self-structured questionnaire and Nordic Musculoskeletal questionnaire. SPSS 21.0 was used for data analysis. Results: A total of 1104 students were included in the study, mean age of the students was 11.90 ± 2.2 (range 8-15) years. There were 48.4% males while 51.6% were females. Frequency of fatigue due to heavy backpack was 61.6%.Neck pain was common in 40.2% students, shoulder pain in 47.4% and the frequency of low back pain was 46.6% .According to BMI 33.2% students had normal BMI and 32.6% students were very severely underweight which is an alarming situation. The correlation of bag pack weight with students BMI was weak positive(r=0.25, p<0.05). Conclusion: This study concluded that the frequency of musculoskeletal pain was high due to carrying heavy backpacks. Upper and low back pain were the most common type. Maximum students carry >16% ratio of backpacks load. Wearing time of backpack was more than 10 minutes.

Electric bus platform for urban mobility

Today, the technology of automatic battery charging based on Wireless Power Transfer (WPT) for the electric mass transit industry involving electric trains, buses and trams, is being used more and more. The modern solution described in this paper proposes an innovative technology for mixed charging of electric buses, either by wireless charging for 2-3 minutes in selected stations, or by plug-in charging at the end of the bus line, which results in only minimal energy storage on board - practically enough to get to the next charging station. The reduction of the weight of the battery packs determines the increase of the number of passengers transported, but also a reduction of the purchase price of the bus, without reducing the performances. The conversion can cost about half the price of new electric buses, depending on the condition of the vehicle and the extent of the work. This solution can be applied especially for the conversion of Diesel buses into electric buses which is not only sustainable, but also significantly better in terms of investment and operational costs, comparing with the purchase of new electric buses.

Comparative analysis of powertrain optimization for Small electric vehicle based on range and weight for Retro-fitment

Range anxiety starts from the battery pack in an electric vehicle. It is one of the areas, where plenty of research is in progress on the development of battery packs. In Small Electric Vehicle (SEV), especially with retro fitment scenario, the floor-mounted battery pack is difficult. This paper focuses on proposing the battery pack concepts for SEV to maximize the range and weight distribution. In this paper, SEV is proposed for urban mobility requirements and the battery pack is mounted on the front and rear hood, which is based on the volume available for mounting in the SEV. Motor for SEV is taken from literature and the powertrain is optimized based on weight and range of SEV. The battery packs considered in this paper are Lead-acid, Nickel Metal Hydride, Lithium Polymer, Lithium-Sulfur, and Zinc-air. Range estimation is done for all the battery packs. Based on the projected battery pack weight at the front and rear hood, Weight distribution is given higher importance in the optimization of battery packs apart from range including its mounting. The Weight distribution is analyzed by keeping the Body in White (BIW) of SEV as constant and different variants of electric powertrains proposed.

The impact of microcellular structures on the sound absorption spectra for automotive exhaust performance mufflers

The role of microcellular structures on the sound absorption spectra of packed structures for automotive exhaust performance mufflers are presented herein, via numerical modelling and simulation. Numerical simulations involving the application of Attenborough’s empirical model are demonstrated to be a better predictor for the sound absorption properties for packed beds of near-spherical structures, with reasonable scatter, when compared to experimental data substantiated in contemporary literature. By varying the packing arrangement for packed samples and stacking with differential microcellular structures, improvements in the absorption properties were achieved – thereby highlighting the dependence of propagated pressure waves on the structural configuration, positioning and thickness of soundproofing materials. This approach could assist in the implementation of microcellular structures in reducing unwanted engine noise, reduction in packing weight and improved active product lifetime of miniaturized soundproofing package in automotive exhaust performance mufflers.

Effect of thermal environments on fast charging Li-ion batteries

Battery thermal management systems (BTMSs) are expected to keep the battery temperature at a moderate level (∼30 °C) to minimize the thermally exacerbated degradation. However, during fast charging, a strong cooling system is required to restrict the temperature rise of Li-ion batteries (LiBs), which significantly increases the cost and weight of battery packs, and induces a large temperature variation inside the battery. In this work we find that all these drawbacks could be relieved by allowing LiBs to charge at higher temperatures. Since the fast charging of a LiB only takes a tiny fraction of its lifetime, the aging rate is limited even at a charging temperature of 60 °C. Three types of thermal environments are proposed: kept constant at 30 °C, preheated to 60 °C, and adiabatic fast charging. With an experimentally validated electrochemical-thermal (ECT) coupled model, we explore the interplay between thermal management and the fast-charging performance. It is found that a gradually increasing temperature profile is the best option to balance the lithium plating and thermal management of the battery. Combining adiabatic fast charging with a preheating step, we can achieve minimal cooling need, perfect temperature uniformity within a battery, and fast-charging capability simultaneously.

Passive Thermal Management in Lithium-Ion Battery Systems via Multilayered Phase Change Materials

With the emerging presence of lithium-ion batteries in aerospace vehicle applications, weight, volume, and safety of lithium-ion battery packs must be addressed with renewed concernment. A thermal runaway event of a single cell can generate temperatures exceeding 600°C, potentially destroying the entire battery pack along with sensitive equipment critical to vehicle operations. If thermal runaway could be contained to a single cell, it would substantially reduce the risk of damage to the vehicle, potentially enabling mission operations to continue. Due to their relatively low mass, low thermal conductivity, versatile formability, and high heat absorption properties, phase change materials (PCM) are a strong candidate for engineering thermal management into lithium-ion battery packs. Herein, seven PCM-based pads, enhanced by novel flame-retardant and intumescent coatings, are evaluated for their ability to prevent thermal runaway propagation. Thermal runaway is initiated via nail penetration in modules of three 11.7Ah, pouch format, NMC lithium-ion cells at 100% SOC, with a pad between each cell. Computational models of the pad samples are developed based on the experimental data, and are also presented in this work.

Novel Graphene Wool Gas Adsorbent for Volatile and Semivolatile Organic Compounds.

Volatile and semivolatile organic compounds in ambient air and occupational settings are of great concern due to their associated adverse human health and environmental impacts. Novel graphene wool samplers have been developed and tested to overcome limitations of commercially available sorbents that can only be used once and typically require solvent extraction. Graphene wool (GW) was synthesized by non-catalytic chemical vapor deposition with optimized conditions, resulting in a novel fibrous graphene wool that is very easy to manage and less rigid than other forms of graphene, lending itself to a wide range of potential applications. Here, the air pollutant sampling capabilities of the GW were of interest. The optimal packing weight of GW inside a glass tube (length 178 mm, i.d. 4 mm, o.d. 6 mm) was investigated by the adsorption of vaporized alkane standards on the GW, using a condensation aerosol generator in a temperature-controlled chamber and subsequent detection using a flame ionization detector. The optimized GW packing density was found to be 0.19 mg mm–3 at a flow rate of 500 mL min–1, which provided a gas collection efficiency of >90% for octane, decane, and hexadecane. The humidity uptake of the sampler is less than 1% (m/m) for ambient humidities <70%. Breakthrough studies showed the favorable adsorption of polar molecules, which is attributed to the defective nature of the graphene and the inhomogeneous coating of the graphene layers on the quartz wool, suggesting that the polar versus non-polar uptake potential of the GW can be tuned by varying the graphene layering on the quartz wool substrate during synthesis. Oxidized domains at the irregular edges of the graphene layers, due to a broken, non-pristine sp2 carbon network, allow for adsorption of polar molecules. The GW was applied and used in a combustion sampling campaign where the samplers proved to be comparable to frequently used polydimethylsiloxane sorbents in terms of sampling and thermal desorption of non-polar semivolatile organic compounds. The total alkane concentrations detected after thermal desorption of GW and PDMS samplers were found to be 17.96 ± 13.27 and 18.30 ± 16.42 μg m–3, respectively; thus, the difference in the alkane sampling concentration between the two sorbent systems was negligible. GW provides a new, exciting possibility for the monitoring of organic air pollutants with numerous advantages, including high sampling efficiencies, simple and cost-effective synthesis of the thermally stable GW, solvent-free and environmentally friendly analysis, and, importantly, the reusability of samplers.

Scalable constrained attributes/issues about risk, reliability and optimization in large scale battery pack

This study focuses on the optimization of scalable battery pack designs, as a scalable battery pack design can tolerate cell failures, implement a fail-safe mode, rapidly reconfigure itself, and adequately supply the load without interruptions. Hot-swapping, bypass mechanisms, configurability, and redundancy are the key attributes of scalable architecture, which enable the batteries to perform the aforementioned tasks. Scalable designs proposed in the literature still have many limitations, such as suboptimal utilization of the battery packs, low practicality, risk of internal short-circuiting of the batteries, increased weight and size of the battery packs, reliability issues under variable loads, and undesired delays in the reconfiguration of switches. The attributes and issues identified above form the basis of this study. First, the concept of practicality is highlighted for realization of scalable designs in real applications. Scalability associated issues, such as switching risk and sub-optimal sizing are explored. The tree algorithm is applied to develop a scalable design with higher power reliability and faster power redistribution. An SOH balancing method is proposed to optimize the utilization of battery pack. Sample of scalable designs and a physics-based electrochemical battery model are used to implement the proposed algorithms. The results confirm that the proposed SOH balancing can prolong the battery life. Additionally, the tree algorithm based design improves the power reliability, and enables fast redistribution of power.

Experimental and Numerical Investigation of the Thermal Performance of a Hybrid Battery Thermal Management System for an Electric Van

The temperature and the temperature gradient within the battery pack of an electric vehicle have a strong effect on the life time of the battery cells. In the case of automotive applications, a battery thermal management (BTM) system is required to maintain the temperature of the cells within a prescribed and safe range, and to prevent excessively high thermal gradients within the battery pack. This work documents the assessment of a thermal management system for a battery pack for an electric van, which adopts a combination of active/passive solutions: the battery cells are arranged in a matrix or composite made of expanded graphite and a phase change material (PCM), which can be actively cooled by forced air convection. The thermal dissipation of the cells was predicted based on an equivalent circuit model of the cells (LG Chem MJ1) that was empirically calibrated in a previous study. It resulted that, in order to keep the temperature of the battery pack at or below 40 °C during certain charge/discharge cycles, a purely passive BTM would require a considerable amount of PCM material that would unacceptably increase the battery pack weight. Therefore, the passive solution was combined with an air cooling system that could be activated when necessary. To assess the resulting hybrid BTM concept, CFD simulations were performed and an experimental test setup was built to validate the simulations. In particular, PCM melting and solidification times, the thermal discrepancy among the cells and the melting/solidification temperatures were examined. The melting time experimentally observed was higher than that predicted by the CFD model, but this discrepancy was not observed during the solidification of the PCM. This deviation between the CFD model results and the experimental data during PCM melting can be attributed to the thermal losses occurring through the mock-up casing as the heating elements are in direct contact with the external walls of the casing. Moreover, the temperature range over which the PCM solidifies was 6 °C lower than that estimated in the numerical simulations. This occurs because the simple thermodynamic model cannot predict the metastable state of the liquid phase which occurs before the onset of PCM solidification. The mockup was also used to emulate the heat dissipation of the cells during a highway driving cycle of the eVan and the thermal management solution as designed. Results showed that for this mission of the vehicle and starting from an initial temperature of the cells of 40 °C, the battery pack temperature could be maintained below 40 °C over the entire mission by a cooling air flow at 2.5 m/s and at a temperature of 30 °C.

The study on a new method of preparing PMMA forming composite bipolar plate

The recent oil resource shortage has prompted the development of the proton exchange membrane fuel cell (PEMFC) system. PEMFC is a possible source of power that can be used in aircraft, household electricity, agriculture, fishing, motor vehicles, ships, submarines, bicycles, and other portable power systems in the future. This paper emphasizes the production of lightweight bipolar plates to solve several existing problems in the PEMFC system, including weight, cost, and integration. Conventional bipolar plates account for approximately 90% of the weight of battery packs. Therefore, an injection molded flow-field plate constructed from polymethylmethacrylate (PMMA) is developed herein to reduce the weight of the PEMFC system. Computer-aided engineering (CAE) mold flow analysis is then used to simulate the experimental design based on the finished products. Experimental analysis is also performed on the adhesion results of the plates. The results indicate that the establishment of the injection mold using CAE simulation improves mold development and reduces cost. Mechanical coarsening on the surface of the PMMA results in improved adhesion (> 50 N) at temperatures higher than 80 °C. Thus, mechanical coarsening is suitable for the PEMFC system. The problem of conventional weight is solved by reducing the weight by 70%.

The feasibility of heavy battery electric trucks

Summary Research on the decarbonization of transport often concludes that heavy battery electric trucks are infeasible due to the incompatibility of long driving distance with high energy use and low specific energy and high costs of batteries. However, emphasis is often placed on battery electric range matching that of diesel trucks, instead of overall competitiveness. We model battery electric trucks that use high-power fast charging, enabling smaller batteries and showing that the economics of battery electric trucks per ton-kilometer improves with greater weight, driven by increasing load capacity as well as increased energy savings as a function of weight. Furthermore, we show that previous findings that the competitiveness per kilometer is worse for heavy trucks than for lighter trucks are very sensitive to assumptions about the battery cost per kWh and lifetime of the battery pack. Given the rapid development of batteries, we conclude that the economic feasibility of heavy battery electric trucks might have been generally underestimated.

Adopting a Conversion Design Approach to Maximize the Energy Density of Battery Packs in Electric Vehicles

Innovative vehicle concepts have been developed in the past years in the automotive sector, including alternative drive systems such as hybrid and battery electric vehicles, so as to meet the environmental targets and cope with the increasingly stringent emissions regulations. The preferred hybridizing technology is lithium-ion battery, thanks to its high energy density. The optimal integration of battery packs in the vehicle is a challenging task when designing e-mobility concepts. Therefore, this work proposes a conceptual design procedure aimed at optimizing the sizing of hybrid and battery electric vehicles. Particularly, the influence of the cell type, physical disposition and arrangement of the electrical devices is accounted for within a conversion design framework. The optimization is focused on the trade-off between the battery pack capacity and weight. After introducing the main features of electric traction systems and their challenges compared to conventional ones, the relevant design properties of electric vehicles are analyzed. A detailed strategy, encompassing the selection of battery format and technology, battery pack design and final assessment of the proposed set-up, is presented and implemented in an exemplary application, assuming an existing commercial vehicle as the reference starting layout. Prismatic, cylindrical and pouch cells are configured aiming at achieving installed battery energy as close as possible to the reference one, while meeting the original installation space constraint. The best resulting configuration, which also guarantees similar peak power performance of the reference battery-pack, allows reducing the mass of the storage system down to 70% of its starting value.

Experimental and Numerical Studies on Materials for Electric Vehicle Chassis

This paper presents experimental and numerical studies on materials for electric vehicle chassis design, testing, and analysis. The chassis for a car should have good rigidity and should be light in weight which are very crucial parameters. To create any car frame is the basic and main structure. It connects rear and front suspension rigidly. Along with this it provides support to the various components of the car. This paper describes the simulation of electric vehicle (EV) Chassis frame with square beam for finding stress, strain and deformation properties in structural body by using finite element analysis (FEA) tools and strain gauge. In this case of chassis structure, we are considering engine weight, alternator weight, motor weight as well as battery pack weight. The total weight on chassis structure is approximately around 4 ton. We are working on finding maximum stress, maximum strain and deformation in structural body by using FEA tools as well as strain gauge.