Search Results (16)

To address the problem of concave bank scour in a 120° bend river, this study designed and explored the bank protection effect of different arrangements of semi-cylinder sandbags. Based on the actual riverbed structure, a simplified geometric model of the bend riverbed was constructed, and the bank protection effect of sandbags arranged at different angles and spacings under different flow conditions was evaluated by using a multi-objective genetic algorithm (MOGA). The optimization results showed that the net sediment mass flow rate of the riverbed in the curved riverbed model using one semi-cylinder sandbag was maximum when the angle between the semi-cylinder sandbag and the concave bank of the riverbed was 158°. Further, the results of the analyses of velocity and spacing indicated that the effect of inlet flow velocity on the effectiveness of bank protection is 1.5 times greater than the spacing of the throw pillows in a bend channel with two semi-cylindrical sandbags. In the conventional flow velocity range of 1~2 m/s, the net sediment mass flow rate in the riverbed is the largest when the throw pillow distance is set at 49 m, which is about 9.4 kg/s, which can provide a better bank protection effect and can provide a certain reference for the design of engineering bank protection. Full article

Background: Fitness is relevant for firefighter occupational performance, but its influence on exertion and cognition during occupational tasks remains unclear. We aim to determine fitness’s influence on performance, exertion, and cognition during simulated firefighter occupational tasks. Methods: Two baseline fitness assessments occurred to measure aerobic fitness, strength, power, and body composition in 33 non-firefighter participants (females/males: 15/18; 25.18 ± 4.06 years; 174.01 ± 9.77 cm; 75.94 ± 13.18 kg). A third visit involved participants completing an occupational task assessment (OTA; four rounds of deadlifts, sandbag carries, and a cognitive assessment at 35 °C/50% humidity) to the best of their ability. Multiple linear regression models, including strength and power, aerobic capacity, and body composition, were used to predict OTA performance and exertion. Our outcomes included time to complete, exertion, and cognitive performance during the OTA. Results: The model predicted OTA time, RPE, skin temperature, and blood lactate (ps < 0.02), but not core temperature (p > 0.24). The model did not predict cognitive errors (ps > 0.06). Conclusions: These metrics of fitness provide meaningful predictive insight into firefighters’ occupational readiness during simulated occupational tasks. Full article

With the increasing emphasis on environmental sustainability, the electrification of urban public bus fleets has gained significant attention. Understanding the factors influencing the energy consumption of battery-electric buses (BEBs) is crucial for enhancing their energy efficiency. Therefore, it is crucial to identify the subsystems that contribute most to energy consumption and understand how operational factors influence them. This paper presents a comprehensive analysis of BEB energy consumption based on experimental measurements performed with a 12 m fully electric battery bus. The main limitations of this study stem from the use of a single vehicle over a total period of 18 days, during which 187 routes were completed. Additionally, sandbags were used as ballast in place of actual passengers. Various parameters, including the number of passengers, drivers, route characteristics, environmental conditions, and traffic, were analyzed to assess their impact on BEB energy consumption. Data related to the energy consumed by various bus utilities were collected through the vehicle’s CAN network, with a sampling rate of 1 measurement per second. These data were analyzed both daily and per route, revealing the breakdown of energy consumption among different utilities and highlighting those responsible for the highest energy use. The results correlate the total distance traveled, service duration, average speed, driver’s driving style, route characteristics, internal and external temperatures, and air-conditioning system’s reference temperature with the energy consumption of the traction motors and climate control system. In addition, the correlation between the driver, vehicle acceleration, and throttle pedal use, and the energy consumed by the electric traction motor is presented. Full article

The small rhizome Chinese herbal medicine harvesting machine is used for excavating the underground rhizomes of Chinese medicinal plants. The reliability of an existing machine of this type was found to be suboptimal due to high vibration levels, as confirmed by direct measurements. To remedy this issue, the differential equation of motion was derived, solved, and visualized using MATLAB software (R2017a). The impact of various parameters on the equation of motion was analyzed through both time and frequency domain plots, as well as experimental analysis. The parameters studied included the rotational speed of the tractor’s power take-off (PTO) shaft, the machine’s overall mass and stiffness, the transmission ratio, and the excitation force generated by the machine’s reciprocating parts. To reduce vibration in the non-resonant state and avoid resonance as the natural frequency changes, several modifications were necessary: the PTO speed needed to be controlled, the stiffness of the machine had to be increased, and the mass of the reciprocating parts had to be decreased. Additionally, expanding the transmission-ratio range of the operational machinery was essential. Sandbags were added to the machine’s frame to increase its overall mass. The above measures have reduced the vibration speed of the harvester during operation. The vibration speeds V_max and V_RMS of the harvester under both working and non-working conditions have decreased by half compared to their original values, reducing the occurrence of resonance in the harvester and effectively mitigating vibration damage, thereby enhancing operational reliability. Full article

This study aimed to evaluate the mechanism of progression involved in knee osteoarthritis (OA). We used the computed tomography-based finite element method (CT-FEM) of quantitative X-ray CT imaging to calculate and create a model of the load response phase, wherein the greatest burden is placed on the knee joint while walking. Weight gain was simulated by asking a male individual with a normal gait to carry sandbags on both shoulders. We developed a CT-FEM model that incorporated walking characteristics of individuals. Upon simulating changes owing to a weight gain of approximately 20%, the equivalent stress increased extensively in both medial and lower leg aspects of the femur and increased medio-posteriorly by approximately 230%. As the varus angle increased, stress on the surface of the femoral cartilage did not change significantly. However, the equivalent stress on the surface of the subchondral femur was distributed over a wider area, increasing by approximately 170% in the medio-posterior direction. The range of equivalent stress affecting the lower-leg end of the knee joint widened, and stress on the posterior medial side also increased significantly. It was reconfirmed that weight gain and varus enhancement increase knee-joint stress and cause the progression of OA. Full article

Patients with type 2 diabetes mellitus (T2DM) are at a three-fold increased risk of developing sarcopenia compared to those without diabetes. The objective of this study was to investigate whether an intervention involving progressive sandbag exercises is beneficial to patients with T2DM and possible sarcopenia in terms of enhancing muscle strength and controlling blood sugar levels. Forty patients with T2DM and possible sarcopenia (age > 50 years) were recruited and randomly divided into resistance training and control groups. Resistance exercises for the upper and lower extremities were performed using sandbags (0.5 kg at the beginning to 1 kg after 1 month). Patients in the control group were asked to maintain their usual daily lifestyle. After 12 weeks, the training group were significant better than the control group in terms of glycosylated hemoglobin, the five times sit-to-stand test, skeletal muscle mass and calf circumference, and the physiological domain of the World Health Organization Quality of Life Questionnaire. In conclusion, these simple home exercises are beneficial to patients with T2DM combined with possible sarcopenia. This approach can assist patients in controlling their levels of glycosylated hemoglobin as well as improve physical fitness and quality of life. Full article

The recent trend in coastal research centers around environmental sustainability, especially in coastal conservation. A seawall typically has three layers, namely core, filter, and hard rubble/concrete armor. In the current study, a two-layered seawall is proposed, comprising a coir geotextile roll from the coastal regions, along with sand encapsulated in a geotextile over an impermeable core. This can be considered as a quasi-soft solution against the traditional, three-layered, hard alternative. The objective of this study is to investigate the combined effect of slope and porosity, of this composite structure, on the wave reflection. The findings show that the composite structure provides less reflection coefficient values compared to traditional rubble mound seawalls. Four orientations and positions of coir rolls with geosynthetic sandbag were tested. The armor layer with coir rolls overlain by geosynthetic sandbags over an impermeable core could be a better alternative, as it increases the hydrodynamic performance by 59% as compared to sandbags, used alone, over an impermeable core on a slope of 1:2. Full article

The Community Care Station (CCS) service was initiated by the Taiwanese government as a part of its elderly social services programs. This study aimed to investigate the effects of using an inexpensive exercise toolkit, containing a stick, theraband, sandbag and a small ball, led by a physical therapist among community-dwelling older adults participating in CCS. A total of 90 participants (aged 77.0 ± 6.8 years) were recruited and divided into an intervention group (n = 45) and a comparison group (n = 45). The intervention group regularly participated in a health promotion program with the exercise toolkit for approximately 90 min per twice-weekly session for 3 months, and the comparison group maintained their usual CCS activity program. Both groups were assessed before and after the 3-month intervention period. Outcome measures included the Short Physical Performance Battery (SPPB), one-leg stance, functional reach (FR), Timed Up and Go (TUG), and 10 m walk tests; 83 participants completed the study. No significant between-group differences were found at baseline in general characteristics or outcome variables. After 3 months, the intervention group showed the significant group x time interaction effects in SPPB, one-leg stance, FR, TUG and 10 m walk tests compared to the comparison group (p < 0.05).; A structured group-based health promotion program using a low-cost exercise toolkit could be effective in improving the physical performances, balance, and walking ability of community-dwelling older adults receiving CCS program services. Furthermore, the comparison group maintained most of their physical performances, even showing significant progress on FR. Full article

There is a high level of homelessness in South Africa. Sandbag building technologies (SBTs) have been offered as economical and sustainable alternative building materials capable of speeding housing provision in South Africa. However, their degree of adoption in South Africa remains relatively low. Furthermore, limited research has examined the low adoption and social acceptance of SBTs, requiring thorough research. Therefore, this research investigates the key social barriers to accepting SBTs in housing provision. The study adopted a mixed method research approach that employs a comprehensive literature review in identifying 18 social barriers to using SBTs and a questionnaire survey of 228 building experts based in South Africa to obtain empirical data. The study findings indicated that the significant impediments were related to the lack of understanding of the benefits of sandbags, a lack of sandbag courses and training, and a lack of professional knowledge and skills, among others. A comparative analysis of the perceptions of the diverse categories of survey participants was conducted and discussed. This study’s evaluation of significant barriers offers government agencies and construction partners a framework to make realistic and well-informed decisions toward more sustainable and affordable housing delivery. Full article

In this study, granulated activated charcoal (GAC) and bio charcoal (BC) is used as a filler in P3 biosand bag filter to study their filtration performance against a range of fluoride impurities from 1–1400 mg/L. A set of experiments are done to analyze the filtration efficiency of the sandbag filter against fluoride impurities after incorporating different amounts (e.g., 0.2, 2 kg) and a combination of GAC and BC. A combination of filler GAC and BC (1 kg each) have exhibited excellent results with 100% fluoride removal efficiency against 5 mg/L fluoride impurities for an entire experimental time of 165 min. It is because of the synergetic effect of adsorption caused by the high surface area (739 m²/g) of GAC and hydroxyapatite groups in BC. The data from remediation experiments using individual GAC and BC are fitted into the Langmuir and Freundlich Isotherm Models to check their adsorption mechanism and determine GAC and BC’s maximum adsorption capacity (Q_m). The remediation data for both GAC and BC have shown the better fitting to the Langmuir Isotherm Model with a high R² value of 0.994 and 0.970, respectively, showing the excellent conformity with monolayer adsorption. While the GAC and BC have presented negative Kf values of −1.08 and −0.72, respectively, for Freundlich Model, showing the non-conformity to multilayer adsorption. The Q_m values obtained from Langmuir Model for GAC is 6.23 mg/g, and for BC, it is 9.13 mg/g. The pH study on adsorption efficiency of individual GAC and BC against 5 mg/L of fluoride impurities indicates the decrease in removal efficiency with an increase in pH from 3 to 9. For example, BC has shown removal efficiency of 99.8% at pH 3 and 99.5% at pH 9, while GAC has exhibited removal efficiency of 96.1% at pH 3 and 95.9% at pH 9. Importantly, this study presents the significance of the synergetic application of GAC and BC in the filters, where GAC and BC are different in their origin, functionalities, and surface characteristics. Full article

In temperate forests, climate seasonality restricts the photosynthetic activity of primary producers to the warm season from spring to autumn, while the cold season with temperatures below the freezing point represents a period of strongly reduced plant activity. Although soil microorganisms are active all-year-round, their expressions show seasonal patterns. This is especially visible on the ectomycorrhizal fungi, the most abundant guild of fungi in coniferous forests. We quantified the production of fungal mycelia using ingrowth sandbags in the organic layer of soil in temperate coniferous forest and analysed the composition of fungal communities in four consecutive seasons. We show that fungal biomass production is as low as 0.029 µg g⁻¹ of sand in December–March, while it reaches 0.122 µg g⁻¹ in June–September. The majority of fungi show distinct patterns of seasonal mycelial production, with most ectomycorrhizal fungi colonising ingrowth bags in the spring or summer, while the autumn and winter colonisation was mostly due to moulds. Our results indicate that fungal taxa differ in their seasonal patterns of mycelial production. Although fungal biomass turnover appears all-year-round, its rates are much faster in the period of plant activity than in the cold season. Full article

Perverse incentives are ubiquitous in different economic settings. In sports, they often take the form of temptation to deliberately lose matches (the phenomenon known as tanking or sandbagging). In practice, there were even such pathological situations as when a soccer team intentionally scored an own goal. We show how and when the temptation is generated by the current pair matching method, the one applied after the first phase of many popular tournaments, including the most prestigious soccer championships. If the organizers of important sporting contests do not introduce any organizational innovations, they risk serious match-fixing scandals. We introduce an alternative procedure and show that its practical implementation could radically mitigate the risk. We perform a comparative analysis of the methods. We analyze the format “Winners and Runners-up Advancing from Two Adjacent Groups”, particularly its FIFA World Cup variant. In order to quantify the benefits of switching from the current method to the proposed one, we refer to simulation results. The expected decrease in temptation probability is about 83% and could be even about 90% if we additionally implement the suggested scheduling innovation. Full article

This study proposes a minimal modeling magnetic, angular rate and gravity (MARG) methodology for assessing spatiotemporal and kinematic measures of functional fitness exercises. Thirteen healthy persons performed repetitions of the squat, box squat, sandbag pickup, shuffle-walk, and bear crawl. Sagittal plane hip, knee, and ankle range of motion (ROM) and stride length, stride time, and stance time measures were compared for the MARG method and an optical motion capture (OMC) system. The root mean square error (RMSE), mean absolute percentage error (MAPE), and Bland–Altman plots and limits of agreement were used to assess agreement between methods. Hip and knee ROM showed good to excellent agreement with the OMC system during the squat, box squat, and sandbag pickup (RMSE: 4.4–9.8°), while ankle ROM agreement ranged from good to unacceptable (RMSE: 2.7–7.2°). Unacceptable hip and knee ROM agreement was observed for the shuffle-walk and bear crawl (RMSE: 3.3–8.6°). The stride length, stride time, and stance time showed good to excellent agreement between methods (MAPE: (3.2 ± 2.8)%–(8.2 ± 7.9)%). Although the proposed MARG-based method is a valid means of assessing spatiotemporal and kinematic measures during various exercises, further development is required to assess the joint kinematics of small ROM, high velocity movements. Full article

This study compared physiological responses and cognitive performance during simulated work activities in heat to a thermoneutral condition. First responders perform physically demanding activities in a hot environment which may impose additional burdens on tactical personnel during daily tasks. Ten healthy (8 men and 2 women) participants performed two consecutive simulated work activities with two repetitions of each activity (10 min walking on treadmill and 15 sandbag lifts) under heat and thermoneutral conditions. A Stroop color word test (SCWT) and total mood disturbance (TMD) were obtained at first and second baseline (B1, B2), after a 30-min resting period (B3), and recovery (R1). At the end of the trial, core temperature (Tc), skin temperature (tsk), and mean body temperature (Tb) were higher in the heat condition compared to neutral condition (all p ≤ 0.05), whereas oxygen uptake, heart rate, and mean arterial pressure were not significantly different between conditions. There were no differences in scores of SCWT and TMD between conditions. However, TMD was significantly improved after two successive bouts of exercise compared to B3 (all p ≤ 0.05). This investigation shows that two successive simulated work activities did not induce the detrimental influence on thermoregulatory and cognitive responses. Extended work activities in a hot and humid environment may impose a psychophysiological burden and need to be investigated. Full article

Open channel levees are used extensively in hydraulic and environmental engineering applications to protect the surrounding area from inundation. However, levees may fail to produce an unsteady flow that is inherently three dimensional. Such a failure may lead to a destructive change in morphology of the river channel and valley. To avoid such a situation arising, hydraulic laboratory modeling was performed on an open channel levee breach model capturing velocity, in x, y and z plans, at selected locations in the breach. Sandbags of various shapes and sizes are tested for incipient motion by the breach flow. We found that a prism sandbag has a better hydrodynamic characteristic and more stability than spherical bags with the same weight. Experimental results are then used to evaluate existing empirical equations and to develop more accurate equations for predicting critical flow velocity at the initial stage of sandbag motion. Results showed the superior predictions a few of the equations could be considered with an uncertainty range of ±10%. These equations explained the initial failed attempts of the United States Army Corps of Engineers (USACE) for breach closure of the case study, and confirmed the experimental results are simulating the case study of breach closure. Full article