Low Walls Research Articles

Identification of physically demanding work tasks among cleaners: field study using electromyography.

While chronic forearm pain is a common and debilitating condition among cleaners, the most physically demanding tasks remain unidentified. The present field study examines forearm muscle activity during 9 common cleaning tasks in a real working environment. Seven healthy cleaners participated in this study (age: 35.17 ± 9.62 yr; height: 168.17 ± 8.06 cm; weight: 77.14 ± 13.78 kg; experience: 5.60 ± 3.29 yr). Surface wireless electromyography (EMG) was recorded from 2 muscles on both sides of the upper limb, flexor carpi ulnaris (FCU), and extensor carpi radialis (ECR), and normalized to maximal voluntary isometric contractions (MVIC). Top-3 demanding high-force tasks (90th percentile EMG) were the rough floor, dirty rough floor, and office floor mopping for the FCU, and mopping high walls, ceiling mopping, and baize cleaning for the ECR. Top-3 static work tasks (10th percentile EMG) were mopping low walls, ceiling mopping, and dirty rough floors mopping for the FCU and mopping of high walls, low walls, and ceiling for the ECR. The study identified the forearm muscles' most physically demanding work tasks during cleaning tasks. The development of better working tools is recommended to avoid high-force overload as well as prolonged static overload of these muscles in cleaners.

A review to the Desert Kite: State of the Art!

Although from the beginning of the historical period, known as the emergence of the writing, it has not passed more than several thousand years, but the history of human evolution can be rooted in an era much older than the one seen: in the age of the hunting-gathering culture! Hunter-gatherer culture was the way of life for early humans until around 11,000 to 12,000 years ago. The lifestyle of huntergatherers was based on hunting animals and foraging for food. Desert kites could be mentioned as a probable transition key from the age of hunting-gathering food to pastoralism, which can be dated today with the development of cosmogenesis and luminescence methods. ‘Desert kites’ are stone constructions made of two long low walls called antennae that converge into an enclosure flanked or not by several small cells. Their shape and archeological evidence suggest that these extensive stone structures may have functioned as game traps, designed to capture and kill large numbers of wild animals. The kite is a landmark that reveals a way of occupying territory. It is an architectural feature of social groups, which hence left a reflection of their territory and catchment. However, these people have sometimes left very few traces enabling their identification. Considering the extent and density of these settlements, the kite is a massive phenomenon whose role was probably crucial in the development of societies in arid regions. It has been seen from the eastern Mediterranean to the eastern Caspian, which suggested finding less of the same structure in the Iranian plateau, as the only suitable linkage, when the northern lands were nearly frozen! Thus, the perspective is reversed from traditional archaeological research, where groups are most often identified by their domestic settlements, with their still undefined modes of subsistence. Kites, as a phenomenon, are therefore a challenge for the archaeology that requires creative and novel approaches.

Crowdfunding Platform Powered by Blockchain Technology

Equity crowdfunding via the Internet is a new channel of raising fund for startups. It features low walls to entry, low cost, and high speed, and therefore encourages invention. In recent times, equity crowdfunding in India has endured some developments. still, some problems remain unsolved in practice. Blockchain is a decentralized and distributed tally technology to ensure data security, transparency, and integrity. Because it cannot be tampered, the technology is supposed to have great eventuality in the finance assiduity. This study examines current problems in the practice of equity crowdfunding in India. Grounded on the analysis of the characteristics of blockchain technology, this study further explores its practical operations in crowdfunding. Blockchain technology is a secure, effective, low- cost result for the enrolment of stocks and shares of a establishment financed by crowdfunding. First, a vendor initiates a request for ensuring a product, then the interested lenders participate in a project Key Words: Blockchain, crowdfunding, Fundraising, Project Registration and Transaction, Voting of Shareholders, Ethereum, Smart Contracts

Statistical Analysis of the Factors influencing the In Situ U-Value of Walls

Building thermal performance testing requires in situ measurement techniques that are well supported and validated by simulation with statistics to improve the accuracy of the results. Local on-site performance of building components is different from the theoretical one, influenced by factors affecting the building's thermal conditions. The current paper reviews the factors influencing the measured U-value results in the heat flux method based on quantitative findings of other studies through regression and correlation statistics. The findings regarding the current status of knowledge are limited to in situ methods without detailed insights of response time, sensitivity analysis, and thermal boundary conditions in the local context. Regression analysis between wall characteristics, time duration, temperature difference, and the measured U-value shows a very strong and statistically significant impact of these variables on the accuracy of the measured U-value of low transmittance walls. The R2 value indicates that three variables can collectively explain 91% of the variance in the measured U-value. There is a linear correlation between the wall characteristics and the measured U-value and a non-linear correlation between the time duration, temperature difference, and the measured U-value. Future work will focus on developing a measurement framework that considers time-dependent variables, dynamic weather, and uncertainty with high accuracy for different boundary conditions.

Exploration of a Rural Street Environment: The Difference in Sight between Villagers and Tourists

This paper takes Nanlizhuang Village, Hebei Province, China, as the object and aims at improving the design of the street-space environment. The real scene of the rural streets is used as the stimulus material, and the difference in eye-movement data between villagers and tourists in the real environment is explored based on eye-tracking technology. This difference is taken as the guiding content for rural space design, and an optimized design strategy is put forward. It is found that visual attractiveness is not only affected by the visual rate of greenery but also closely related to changes in spatial enclosures. The combination of low walls and greenery is conducive to the formation of impression symbols in the village; the collective memory of indigenous villagers is also a major reason for changes in visual gravity. The experiment proves the feasibility of using real scenes as rural street design strategies through eye-tracking technology.

Numerical study on the impact of traffic lane adjustments and low boundary walls on pedestrian exposure to NO2 in street canyons

Mitigating the adverse effects of air pollution, especially on human health, is one of the greater contemporary challenges for cities. Street canyons have herein been identified as bottleneck areas in urbanized environments. Focusing on the necessity of fast-response interventions, strategies to control source-receptor pathways (e.g. implementing low boundary walls (LBWs)) are gaining interest. A potential strategy which is greatly overlooked is the adjustment (reduction or displacement) of traffic lanes in order to increase the distance between source (traffic) and recipient (pedestrians). Within our study, computation fluid dynamics (CFD) is used to simulate the impact of alternations to traffic lanes (whether or not combined with LBWs) on the pedestrian exposure to NO2 for a specific case-study (Belgiëlei, Antwerp) under two prevailing wind directions. The average differences in NO2 concentrations for the entire pedestrian area ranged between +1.0 % to −3.6 %. On specific locations, reduction up to −8.0 % were reached. In case of perpendicular winds, a lateral displacement of all traffic lanes towards the windward facade including LBWs was found most beneficial to reduce pedestrian exposure. LBWs also showed to be efficient in reducing potential adverse effects of lane displacement under less frequent wind directions.

Robust multi-objective building design optimization approach using NSGA-II algorithm considering weather and occupant uncertainties

A novel methodology is presented to evaluate how real-world operational uncertainties impact multi-objective building design optimization process. NSGA-II algorithm is applied across nine distinct operational scenarios, considering diverse weather datasets and energy usage patterns to optimize energy efficiency and thermal comfort in a residential building within India's hot and dry climate. The analysis considers 382,400 possible design options for each scenario. Using (10.5–12.5) % of model evaluations, NSGA-II significantly reduces Annual Cooling Energy Demand (ACED; 46.7%–58.7%) and Cooling Set-point Unmet Hours (CSUH; 70.92%–86.93%) to identify nine Pareto–Optimal solution sets. The final robust optimal design is confirmed by selecting the most repeated parameter settings, representing the highest robustness. Low thermal transmittance walls, double-glazed windows with a 10% window-to-wall ratio (WWR), deep overhangs, and a low solar heat gain coefficient are recognized as robust optimal building components. However, Air Conditioner (AC) sizing lacks robustness in minimizing energy demand across scenarios, requiring case-specific evaluation due to its sensitivity to weather and operational variations. Further, PAWN sensitivity analysis highlighted the substantial impact of WWR (KSWWR ∼ (0.46–0.66)) and wall type (KSWall ∼ (0.31–0.46)) on ACED and CSUH in chosen climate. AC operation is more important for predicting CSUH (KSAC ∼ 0.35) than ACED (KSAC ∼ 0.10).

Transient Behavior Analysis of the Infiltration Heat Recovery of Exterior Building Walls

This research study investigated the transient behavior of the convection–diffusion model for the infiltration heat recovery (IHR) and the influence of the building envelope heat capacity, along with other factors. A transient numerical model was developed and validated to analyze the IHR under various conditions. The results highlight the role of heat capacity, thermal conductivity, wall thickness, airflow rate, airflow direction, and wall porosity on the temperature distribution and the heat recovery factor within the wall. Higher-heat-capacity walls displayed a delayed temperature rise, while low-thermal-conductivity walls reduced the conduction heat transfer and increased the IHR factor. The impact of heat capacity diminished with very low thermal conductivity walls but became evident for high-thermal-conductivity walls, particularly at higher Peclet numbers. Thicker walls enhanced the heat retention and improved the IHR, with a reduced influence of airflow rate. Higher IHR factors were associated with thicker walls, lower Peclet numbers, and higher heat capacities. The analysis also showed that the wall porosity affected the IHR with less significance than the other factors. Incorporating these findings into building energy modeling tools could improve the prediction accuracy of the thermal behavior of buildings. Accordingly, this study contributes to building physics by understanding IHR dynamics and thermal mass interactions, as well as improving building energy modeling accuracy for performance prediction. Future research can explore the impacts of additional factors on IHR and investigate the effect of IHR on the overall energy consumption of buildings.

Experimental study on seismic performance of low strength shear walls strengthened with modified reactive powder concrete

Improper operation during construction and damages in long-term use environments will result in the shear walls being unable to meet seismic design and safety requirements. In order to further explore the impact of modified reactive powder concrete (MRPC) surface strengthening on the bending performance of shear walls, four shear walls were subjected to low cyclic loading tests. The effects of single-sided strengthening, double-sided strengthening, and different strengthening thicknesses on their seismic performance such as failure mode, deformation capacity, energy dissipation capacity, and stiffness degradation have been studied. The results show that the failure modes of four shear wall specimens were bending failure. Horizontal and oblique cracks appeared at the bottom and middle of the specimen, respectively, and the concrete at the corner was crushed and peeled off. For the specimen strengthened by MRPC, the strengthening layer was slightly warped, and the number of cracks is significantly reduced, which can effectively avoid the brittle failure of the specimen. The strengthening layer formed a good restraint on the internal concrete. MRPC can effectively improve the seismic performance of low bending strength concrete shear walls, and the ductility was far exceeded the expectations of the experiment. Double-sided strengthening was better than single-sided strengthening. Increasing the strengthening thickness can improve the flexural cracking capacity, but due to the interface between the shear wall and MRPC, it had little effect on the yield, peak and ultimate capacity. In addition, excessive thickness will reduce the ductility and energy dissipation capacity of the specimen.

Numerical investigation of the effects of inlet conditions and wall heat transfer on subcritical/transcritical CO2 nozzle performance

In ejector-based refrigeration cycles and CO2 heat pump cycles, inlet flow state and wall heat transfer play an important role in improving nozzle performance. A CO2 two-phase nozzle model was firstly established. Then, the numerical model is validated by experimental data and void fraction correlation, and the effect of condensation coefficient and gas equation of state was analyzed. In addition, the CO2 flow behavior and the thermodynamic performance of the nozzle under different inlet gas phase volume fraction (GVF) and wall conditions (temperature and materials) were studied. The results show that although the GVF can reduce the critical mass flow rate of the nozzle, its adverse impact on the thermodynamic performance of the nozzle is more significant (The GVF varied from 0 to 0.6, with the former decreasing by 10.2% and the latter increasing by 25.1%). Low temperature on the wall will exacerbate the non-equilibrium phase transition, leading to an increase in the critical mass flow rate of the nozzle. At this time, high thermal conductivity walls will also exacerbate exergy losses, by using low thermal conductivity walls can improve the consequences. In addition, the study also found that the inlet supercooling degree (ISCD) should be set between 0 and 7 K, and excessive ISCD would lead to an increase in outlet humidity and a rise in critical mass flow.

Using alkali-activated dredge sludge ash-bentonite for low permeability cutoff walls: The engineering properties and micromechanism

Although vertical cutoff walls can effectively contain groundwater pollution, vertical barriers constructed using conventional cement-bentonite-soil (CBS) mixtures exhibit poor permeability and produce considerable CO2 during cement production. The dredged sludge ash (DSA) has potential to be used as an eco-friendly source for vertical barriers building because of the remarkable pozzolonicity. In this study, a mixture consisting of MgO-activated dredged sludge ash (DSA) and bentonite was used to develop a low permeable MgO-activated DSA-bentonite-sand (MDBS) barrier material for application to vertical cutoff walls. The mechanical properties of MDBS and CBS mixtures were investigated and the hydration products and microstructure were examined using scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), and mercury intrusion porosimetry (MIP). The results showed that the MDBS mixture exhibited excellent impermeability: the hydraulic conductivity of MDBS cured for 60 d reached the minimum (1.83 × 10−8 cm/s), and considerably superior to the common requirement (lower than 10−7 cm/s) for cutoff walls. The unconfined compressive strength of the MDBS cured for 60 d increased by approximately 112% compared to the samples cured for only 7 d. The hydration products in MDBS were mainly magnesium silicate hydrate and hydrotalcite, which filled the material pores more effectively than the hydration products of CBS (calcium silicate hydrate calcium hydroxide and ettringite). The hydration products, bentonite swelling, and pore size distribution determined the MDBS mechanical properties and permeability. It is verified that activated dredge sludge ash can be used as an ideal cutoff walls material instead of cement.

FC-EODR: Immersive Humanoid Dual-Arm Dexterous Explosive Ordnance Disposal Robot

In this study, we proposes a humanoid dual-arm explosive ordnance disposal (EOD) robot design. First, a seven-degree-of-freedom high-performance collaborative and flexible manipulator is developed, aiming at the transfer and dexterous operation of dangerous objects in EOD tasks. Furthermore, an immersive operated humanoid dual-arm dexterous explosive disposal robot (FC-EODR) is designed, which has a high passability to complex terrains such as low walls, slope roads, and stairs. It can remotely detect, manipulate, and remove explosives in dangerous environments through immersive velocity teleoperation. In addition, an autonomous tool-changing system is constructed, which enables the robot to flexibly switch between different tasks. The effectiveness of the FC-EODR is finally verified through a series of experiments, including the platform performance test, manipulator load test, teleoperated wire trimming, and screw-screwing experiments. This letter provides the technical foundation for robots to replace humans in EOD tasks and emergency situations.

Designing Sensory Integration Spaces in Autism Centers (A Descriptive Approach)

According to World Health Organization, it has been proven that autism is on the rise worldwide and has become a significant challenge in education. Therefore, the research aims to (recognise the design of sensory integration spaces in autistic children's centres to improve the learning environment for the autism category. The research hypothesis states that (the process of designing sensory integration spaces in autism centres is achieved through developing various sensory spaces, applying design strategies, and adding elements that will contribute to creating integrated sensory spaces). The research adopted the descriptive analysis method based on the theoretical framework vocabulary extracted from the previous literature. The Art Therapy Cenproject Center, located in the southern region of the United States, was chosen for practical application. Research recommends that when designing spaces for autistic children, taking into account The severity of autism, where each type has a different sensory space. Inflated sense, spaces are white, and lighting devices are colored. While low sense recommends black walls and the use of ultraviolet lighting.

Numerical method for solving coupled heat and mass transfer through walls for future integration into an urban climate model

Numerous studies of hygrothermal transfers through walls have highlighted the impacts of this phenomenon on energy consumption and indoor conditions. However, urban scale models that aim to simulate weather conditions and urban heat island effects within cities neglect moisture transfer through walls. The objective of this paper is to propose a method for solving this phenomenon that could be integrated into an urban climate model. This kind of integration requires the numerical schemes to be adapted as well as the spatiotemporal scales. The proposed method is based on an Implicit/Explicit discretisation scheme and a decoupled numerical approach for solving. Numerical stability is ensured by reducing the time step in critical moments, which are detected by five tests. This method is validated by comparison with a reference model (Delphin ®), on several study cases using different wall compositions and climates. A mesh sensitivity analysis is performed and shows that low permeability walls require a finer mesh than walls made of highly hygroscopic or capillary active materials. Furthermore, the more layers there are in the wall, the finer the mesh size needs to be. This numerical method allowed a balance to be found between computational cost and accuracy level in accordance with the expectations for an urban climate model. The future integration of this method into an urban climate model will make it possible to carry out energy/climate simulations, including the hygrothermal behaviour of walls, and thus to study its impact at urban scale.

Cyclic model of post-tensioned low damage timber walls with dissipative devices

Post-tensioned rocking dissipative timber wall systems born from the idea to obtain structural solutions able to guarantee, after a seismic event, a rapid re-use of the buildings without permanent damage, as well as to guarantee the safeguarding of human life. In this framework, the rocking of timber walls is entrusted to post-tensioned bars, placed in ad hoc cavities of the panel, while the dissipative contribution is provided by steel dampers, which are sacrificial elements subjected to damage easily replaceable after an intense seismic event. In this context, it can be helpful to have a numerical model in order to support the design phase; indeed, the paper presents a non-linear numerical model of post-tensioned rocking dissipative timber walls able to predict the response of this innovative system. In particular, geometrical and material non-linearities, due to the rocking behavior of the system and to the material that characterize the dampers, are taken explicitly into account. Further, the proposed numerical modelling strategy has been validated on literature experimental campaigns performed on both single and double wall systems, with different damper configurations. The comparison between experimental and numerical cyclic responses are shown in term of global results, i.e. force/displacement curves and post-tension variation of the bars. The comparison demonstrates the effectiveness of the proposed model in predicting the behavior of post-tensioned walls subjected to cyclic loads.

Parametric study of the energy potential of a building’s envelope with integrated energy-active elements

Building structures with integrated energy-active elements (BSIEAE) present a progressive alternative for building construction with multifunctional energy functions. The aim was to determine the energy potential of a building envelope with integrated energy-active elements in the function of direct-heating, semi-accumulation and accumulation of large-area radiant heating. The research methodology consists in an analysis of building structures with energy-active elements, creation of mathematical-physical models based on the simplified definition of heat and mass transfer in radiant large-area heating, and a parametric study of the energy potential of individual variants of technical solutions. The results indicate that the increase in heat loss due to the location of the tubes in the structure closer to the exterior is negligible for Variant II, semi-accumulation heating, and Variant III, accumulation heating, as compared to Variant I, direct heating, it is below 1 % of the total delivered heat flux. The direct heat flux to the heated room is 89.17 %, 73.36 %, and 58.46 % of the total heat flux for Variant I, Variant II and Variant III, respectively. For Variant II and Variant III, the heat storage accounts for 14.84 %, and 29.86 % of the total heat flux, respectively. Variants II and III appear to be promising in terms of heat/cool accumulation with an assumption of lower energy demand (at least 10 %) than for low inertia walls. We plan to extend these simplified parametric studies with dynamic computer simulations to optimise the design and composition of the panels with integrated energy-active elements.

Cyclic behavior of hollow-core precast shear walls subjected to different axial loads

To avoid the brittle failure of low aspect ratio shear walls, a novel hollow-core precast shear wall (HCPSW) with boundary elements is proposed. HCPSW has good collapse resistance and higher out-of-plane lateral resistance compared to a solid shear wall with the same concrete consumption. In this study, the effects of the axial load ratio and horizontal reinforcement on the seismic behavior of HCPSW with low aspect ratios were investigated through eight tests of full-scale shear walls under vertical and lateral loads. The results show that the HCPSW with a low aspect ratio under an axial load ratio in the range of 0.2–0.6 formed the damage development process from the hollow core to other areas of the wall panel, thus avoiding the brittle failure of the overall shear failure. The proposed shear walls consume the seismic energy through concrete cracking along the hollow core. Therefore, the higher the axial load ratio, the higher the energy dissipation capacity because of a larger damage area in the hollow core. Increasing the diameter of the horizontal reinforcement effectively improved the bearing capacity of the specimen and reduced the residual deformation. A numerical model with high accuracy was established to simulate the seismic behavior of the HCPSW and perform parametric studies.

Hybrid Spectrum Sensing Using MD and ED for Cognitive Radio Networks

Day by day, the demand for wireless systems is increasing while the available spectrum resources are not sufficient. To fulfil the demand for wireless systems, the spectrum hole (spectrum vacant) should be found and utilised very effectively. Cognitive radio (CR) is a device which intelligently senses the spectrum through various spectrum-sensing detectors. Based on the complexity and licensed user’s information present with CR, the appropriate detector should be utilised for spectrum sensing. In this paper, a hybrid detector (HD) is proposed to determine the spectrum hole from the available spectrum resources. HD is designed based on an energy detector (ED) and matched detector (MD). Unlike a single detector such as ED or MD, HD can sense the signal more precisely. Here, HD can work on both conditions whether the primary user (PU) information is available or not. HD is analysed under heterogeneous environments with and without cooperative spectrum sensing (CSS). For CSS, four users were used to implement OR, AND, and majority schemes under low SNR walls. To design the HD, specifications were chosen based on the IEEE Wireless Regional Area Network (WRAN) 802.22 standard for accessing TV spectrum holes. For the HD model, we achieved the best results through OR rule. Under the low SNR circumstances at −20 dB SNR, the probability of detection (PD) is maximised to 1 and the probability of a false alarm (PFA) is reduced to 0 through the CSS environment.

Study on the Stress Variation Law of Inclined Surrounding Rock Roadway under the Influence of Mining

This study takes three roadways with similar burial depths in different strata in Xieqiao Mine of Huainan as its research object. This study involves the observation and analysis of borehole stress gauge data under the influence of mining pressure. The observation data show that: (1) under the influence of mining, the high-wall vertical stress increases as the distance from the roadway surface increases, and the peak point is at 6 m. The increment value of vertical stress at the low side has a maximum value at 8 m and a peak value at 14 m. The increase value of horizontal stress of the high side has two peaks, which are 4 m and 6 m, respectively. The increment of horizontal stress in low walls is also about 8 m. (2) The mining influence range of working face mining is about 150 m. Mining influence distance can be divided into three stages: 0–25 m, 25–60 m, and beyond 60 m. The increase of vertical and horizontal stress caused by mining increases sharply within 25 m from the working face. (3) The buried depth of the roadway has an influence on the range of mining influence and the increase of mining stress caused by working face mining. The more the buried depth of the roadway increases, the greater the range of mining influence and the increased value of mining stress. (4) After roadway excavation, the surface deformation of roadway surrounding rock reduces the increase of mining stress near the roadway surface. The mutual verification between the analysis results and theoretical calculation results is helpful to roadway support design and advanced support design of the working face.

COMPARATIVE EVALUATION OF MARGINAL SEALING ABILITY OF POSTERIOR PACKABLE COMPOSITE WITH OR WITHOUT LINERS USING DYE PENETRATION METHOD- AN INVITRO STUDY.

Condensable” or “packable” composites (Surel) were introduced as an alternative to dental amalgam. However, concerns have been raised related to the ability of these stiffer materials to adequately adapt to internal surfaces. To offset this problem, low viscosity owable liners walls are recommended under packable composites. This study aimed at evaluating the effect of SDR and Ketac N100 liners on marginal sealing ability of High Density Surel posterior packable composite. Methodology: Sixty permanent extracted molars were mounted in a modelling wax and box only Class II cavities were prepared on the mesial side with gingival seat 1mm above CEJ. Teeth were divided into 3 groups: Group (i) Surel with SDR; Group (ii) Surel with Ketac N 100; and Group (iii) Surel without liner. After restoration, the teeth were immersed in Methylene blue dye, sectioned mesiodistally and then evaluated for leakage under Stereomicroscope. Results: None of the groups were free of microleakage. Surel without liner (1.2±0.696) exhibited maximum microleakage followed by Ketac N100 group (0.9±0.718) and SDR group (0.8±0.523) showed least microleakage. Conclusion: Posterior packable composites should be lined by a resin based liner at the gingival margin to allow better seal