Research Progress of Aromatic Bed Curtains for Aiding Sleep Based on Lavender Microcapsule Technique

In this paper, the preparation technique of lavender essential oil microcapsules and the construction method of aromatic textiles were expounded, and the research status of bed curtains and lavender microcapsules at home and abroad was analyzed and studied from the perspective of application in textiles. The application of lavender essential oil to bed curtains through the microcapsule technique was put forward to allow lavender essential oil to play its role of helping sleep in bed curtains. This paper expounded the material selection and preparation technique of lavender microcapsule agents, and put forward the preparation method of microcapsules with mixed solutions of pure Chinese medicine extracts and natural essences as core material and high-viscosity epoxy resin as wall materials. The post-processing techniques and the spray ironing method for clothing were studied and developed, and these techniques and methods were applied to bed curtains, and good results were obtained.

EXPERIMENT OF SMOKE-PREVENTING AIR CURTAINS IN HIGH-RISE BUILDING FIRES

In high-rise building fires, the most immediate threat to passenger life and safety evacuation is the smoke inhalation. Some traditional models for smoke prevention and exhaust are analyzed and compared with the smoke-preventing air curtain. The rationality and the feasibility of the air curtain are theoretically expounded. The air volume, tuyere width and jet velocity in the air curtain experiment are designed according to the theoreti- cal calculation model. Experimental results indicate that the effect of air curtain to prevent smoke diffusion is re- markable as the volume ratio of air-smoke is about 0. 6, the jet angle is between 25^o and 35^o, and the jet thickness is between 25 mm and 45 mm. The efficiency of air curtain can reach 98% on the entraining effect. Meanwhile, experiments verify the theorectical calculation.

Permeability in Flysch-Distribution Decrease with Depth and Grout Curtains Under Dams

A considerable number of in situ permeability tests in flysch are processed to a depth of 120m with a good spatial distribution. The distribution of permeability values for the different litho-types of this formation, their comparison and their decrease with depth is discussed. The depth where a permeability of 3 to 5×10-7m/sec can be retained (the limit of a reasonable grouting under a high dam) may be twofold if the geological history of the formation could not contain a compressional tectonic process. This depth may reach 100m in some cases. The differences in the mean values of permeability among the various litho-types are minor, while the presence of siltstones, always present although with varied participation, dramatically controls the global permeability.

Using air curtains to reduce short-range infection risk in consulting ward: A numerical investigation

Air curtains is promising in reducing the short-range infection risk in hospitals.To quantitatively evaluate its performance,this paper explores air curtains equipped on normal consulting desk to avoid doctor’s direct exposure to the patient exhaled pollutants.A numerical investigation is conducted to evaluate the effects of supply air velocity and angle on cutting off performance.Simulation results show that the average mass fraction of exhaled pollutants decreases significantly(70%–90%)in the consulting ward,indicating satisfying performance of air curtains.Increasing supply air velocity is demonstrated to be conducive in forming full air curtains,whereas an excessively high supply air velocity may be of adverse effects by entraining exhaled flow.Besides,the supply air angle is also critical due to its coupling with supply air velocity.It is found that larger angle(0°–40°)is better where velocity is less than 3 m/s,otherwise a small angle(20°)is preferable where velocity is larger than 3 m/s.Exhaled flow could be well suppressed at the supply air angle 20°but moves over air curtains at 40°.This study can provide effective and intuitive guidance in applying air curtains in consulting wards.

SOUND PROPAGATION AND INVERSION IN BUBBLY CURTAINS

An acoustical inversion method to measure parameters, such as the distributions of thesizes, the volume concentration of bubbles and the thickness of the bubbly curtain, is pro-posed. A concept of equivalent incidence is introduced to describe the sound interactionsamong bubbles. Thus, the problem of multiple bodies can be reduced into a single-body one.By taking the distributions in the sizes of bubbles into account, the covibration mass, thedamping constant and the stiffness as well as the complex wavenumber can be given. Thesound interactions result in a dependence of mass and stiffness of bubbles upon frequency.leading to a double-peak resonance, increasing the damping constant and decreasing thesound attenuation. Using the complex wavenumber to denote the wavenumber in bubbly cur-tain, the problem of reflection and transmission from it can be considered as a three-layer-medium one. Optimization methods are used to invert the parameters of the bubbly cur-tains. Comparisons of the the ory with our experiments are given.

Effects of dust controls on respirable coal mine dust composition and particle sizes:case studies on auxiliary scrubbers and canopy air curtain

Control of dust in underground coal mines is critical for mitigating both safety and health hazards.For decades,the National Institute of Occupational Safety and Health(NIOSH)has led research to evaluate the effectiveness of various dust control technologies in coal mines.Recent studies have included the evaluation of auxiliary scrubbers to reduce respirable dust downstream of active mining and the use of canopy air curtains(CACs)to reduce respirable dust in key operator positions.While detailed dust characterization was not a focus of such studies,this is a growing area of interest.Using preserved filter samples from three previous NIOSH studies,the current work aims to explore the effect of two different scrubbers(one wet and one dry)and a roof bolter CAC on respirable dust composition and particle size distribution.For this,the preserved filter samples were analyzed by thermogravimetric analysis and/or scanning electron microscopy with energy dispersive X-ray.Results indicate that dust composition was not appreciably affected by either scrubber or the CAC.However,the wet scrubber and CAC appeared to decrease the overall particle size distribution.Such an effect of the dry scrubber was not consistently observed,but this is probably related to the particular sampling location downstream of the scrubber which allowed for significant mixing of the scrubber exhaust and other return air.Aside from the insights gained with respect to the three specific dust control case studies revisited here,this work demonstrates the value of preserved dust samples for follow-up investigation more broadly.

Stability behavior of the Lanxi ancient flood control levee after reinforcement with upside-down hanging wells and grouting curtain

The stability of the ancient flood control levees is mainly influenced by water level fluctuations, groundwater concentration and rainfalls. This paper takes the Lanxi ancient levee as a research object to study the evolution laws of its seepage, displacement and stability before and after reinforcement with the upside-down hanging wells and grouting curtain through numerical simulation methods combined with experiments and observations. The study results indicate that the filled soil is less affected by water level fluctuations and groundwater concentration after reinforcement. A high groundwater level is detrimental to the levee's long-term stability, and the drainage issues need to be fully considered. The deformation of the reinforced levee is effectively controlled since the fill deformation is mainly borne by the upside-down hanging wells. The safety factors of the levee before reinforcement vary significantly with the water level. The minimum value of the safety factors is 0.886 during the water level decreasing period, indicating a very high risk of the instability. While it reached 1.478 after reinforcement, the stability of the ancient levee is improved by a large margin.

Discussion on Dust Removal(Suppression)System of Crushing Station in Open-Pit Coal Mine

This paper introduces the method of coal dust treatment in crushing station and the present situation of dust removal system in typical open-pit coal mine crushing station in China,and expounds the research idea of determining comprehensive dust removal(suppression)system in crushing station inspired by the working principle of"range hood".Based on the design example and link optimization of the crush-ing station of open-pit coal mine I of Thar coalfield,this paper finally draws some conclusions on the key technologies of dust removal(suppression)system of open-pit coal mine crushing station.This study has certain reference value for the technical innovation of dust removal(suppression)system in crushing station,the realization of green mining in"crushing link",and the reduction and avoidance of ecological environment pollution in mining area.

Innovative Techniques Unveiled in Advanced Sheet Pile Curtain Design

This thorough review explores the complexities of geotechnical engineering, emphasizing soil-structure interaction (SSI). The investigation centers on sheet pile design, examining two primary methodologies: Limit Equilibrium Methods (LEM) and Soil-Structure Interaction Methods (SSIM). While LEM methods, grounded in classical principles, provide valuable insights for preliminary design considerations, they may encounter limitations in addressing real-world complexities. In contrast, SSIM methods, including the SSI-SR approach, introduce precision and depth to the field. By employing numerical techniques such as Finite Element (FE) and Finite Difference (FD) analyses, these methods enable engineers to navigate the dynamics of soil-structure interaction. The exploration extends to SSI-FE, highlighting its essential role in civil engineering. By integrating Finite Element analysis with considerations for soil-structure interaction, the SSI-FE method offers a holistic understanding of how structures dynamically interact with their geotechnical environment. Throughout this exploration, the study dissects critical components governing SSIM methods, providing engineers with tools to navigate the intricate landscape of geotechnical design. The study acknowledges the significance of the Mohr-Coulomb constitutive model while recognizing its limitations, and guiding practitioners toward informed decision-making in geotechnical analyses. As the article concludes, it underscores the importance of continuous learning and innovation for the future of geotechnical engineering. With advancing technology and an evolving understanding of soil-structure interaction, the study remains committed to ensuring the safety, stability, and efficiency of geotechnical structures through cutting-edge design and analysis techniques.

Survey of Shopping Streets as Basic Knowledge for Revitalizing the Old Town Centre of Parma

The revitalization of the historic fabric should not be considered only a matter of safeguarding the cultural heritage of collective memory; it will mainly be to recover and value an urban life, as in the urban context, the historic centre plays a function of social identification and recognition of the community, that commercial distribution helps to keep alive. It is widely spreading the concept of Old Town as Natural Shopping Centre： with this word, we define commercial complex and not homogenous places, developed over time without programming unit. designed as a unique space, which fall within a certain urban perimeter, work together as a business, financial administration, facilities and service all coordinated by a common policy development. In order to recover the vitality of the consolidated tissue of the city of Parma, the Town Council has started to study its historic centre as Natural Shopping Centre, relying on the potential inherent in the existing commercial streets.

Porosity and permeability variations of a dam curtain during dissolution

During reservoir operation,the erosion effects of groundwater change the porosity and permeability of the dam curtain,causing changes to the seepage field.To understand where the changes take place and to what degree the porosity and permeability change,a multi-field coupling model was built and solved.The model takes into account seepage,solution concentration,and solid structure.The model was validated using uplift pressure monitoring data.Then,the variations in curtain porosity,seepage flow,and loss quantity of Ca(OH)2 were calculated.The key time nodes were obtained through curve fitting of the variation of seepage flow with the BiDoseResp function.The results showed that the model could reflect the attenuation trend of curtain performance well.The process and position of the erosion were not homogeneous.Although erosion mainly occurred at the top and bottom of the curtain,it was most developed at the top.The erosion effects developed slowly during the early stage,much fast during the middle and late stages,and culminated in complete dissolution.The model results and the daily monitoring data can provide a scientific basis for the safe operation and management of reservoirs.

Experimental study of water curtain performance for gas storage in an underground cavern

An artificial water curtain system is composed of a network of underground galleries and horizontal boreholes drilled from these galleries.Pre-grouting measures are introduced to keep the bedrock saturated all the time.This system is deployed over an artificial or natural underground cavern used for the storage of gas（or some other fluids） to prevent the gas from escaping through leakage paths in the rock mass.An experimental physical modeling system has been constructed to evaluate the performance of artificial water curtain systems under various conditions.These conditions include different spacings of caverns and cavern radii located below the natural groundwater level.The principles of the experiment,devices,design of the physical model,calculation of gas leakage,and evaluation of the critical gas pressure are presented in this paper.Experimental result shows that gas leakage is strongly affected by the spacing of water curtain boreholes,the critical gas pressure,and the number and proximity of storage caverns.The hydraulic connection between boreholes is observed to vary with depth or location,which suggests that the distribution of water-conducting joint sets along the boreholes is also variable.When designing the drainage system for a cavern,drainage holes should be orientated to maximize the frequency at which they encounter major joint sets and permeable intervals studying in order to maintain the seal on the cavern through water pressure.Our experimental results provide a significant contribution to the theoretical controls on water curtains,and they can be used to guide the design and construction of practical storage caverns.

A SIMPLIFIED CALCULATING METHOD OF NONLINEAR FREQUENCY OF CABLE NET UNDER MEAN WIND LOAD

The cable net supported glass curtain wallas the most advanced technique in dot point supported glass curtain wall, is widely used in China. Because of its large deflection and high nonlinearity under wind load, the dynamic performance of the cable net is greatly different from that of the conventional linear structures. The continuous membrane theory is used to construct the nonlinear vibration differential equation of the cable net, and the harmonic balance method is used to solve the analytic formula of the nonlinear frequency. In order to verify the accuracy of the above analytic formula, the results of the formula and the nonlinear FEM time-history method are compared and found to be in good agreement. Furthermore, the nonlinear vibration differential equation and the nonlinear frequency obtained in this paper are the basis for the wind-induced response analysis of a cable net under fluctuating wind load.

Removal of Pb^(2+) and Cd^(2+) by adsorption on clay-solidified grouting curtain for waste landfills

Pb2+ and Cd2+ in leachate were adsorbed on clay-solidified grouting curtain for waste landfills with equilibrium experiment. The cation exchange capacity was determined with ammonium acetate. And the concentration of heavy metal cations in leachate was determined with atomic absorption spectrophotometer. Their equilibrium isotherms were measured, and the experimental isotherm data were analyzed by using Freundlich and Langmuir models. The results show that the adsorption capacities of the heavy metal cations are closely related to the compositions of clay-solidified grouting curtain, and the maximum adsorption appears at the ratio of cement to clay of 2∶4 in the experimental conditions. At their maximum adsorption and pH 5.0, the adsorption capacities of Pb 2+ and Cd 2+ are 16.19mg/g and 1.21mg/g. The competitive adsorption coefficients indicate that the adsorption of clay-solidified grouting curtain for Pb2+ is stronger than that for Cd 2+ . The adsorption process conforms to Freundlich’s model with related coefficient higher than 0.996.

Calculation of groundwater head distribution with a close barrier during excavation dewatering in confined aquifer

When pumping is conducted in confined aquifer inside excavation pit(waterproof curtain),the direction of the groundwater seepage outside the excavation changes from horizontal to vertical owing to the existence of the curtain barrier.There is no analytical calculation method for the groundwater head distribution induced by dewatering inside excavation.This paper first analyses the mechanism of the blocking effects from a close barrier in confined aquifer.Then,a simple equation based on analytical solution is proposed to calculate groundwater heads inside and outside of the excavation pit with waterproof curtain(hereafter refer to close barrier)in a confined aquifer.The distribution of groundwater head is derived according to two conditions:(i)pumping with a constant water head,and(ii)pumping with a constant flow rate.The proposed calculation equation is verified by both numerical simulation and experimental results.The comparisons demonstrate that the proposed model can be applied in engineering practice of excavation.

Laboratory results of a 3rd generation roof bolter canopy air curtain for respirable coal mine dust control

Testing was completed on an earlier roof bolter CAC that used slots to provide a perimeter airflow. NIOSH tested it due to its unique design that differed from canopies that provided uniform airflow. Based upon NIOSH recommendations from the earlier testing, a 3rd generation roof bolter CAC has been developed by J.H. Fletcher & Co. The changes to this CAC involve design modifications to the plenum outlets, using a single row of outlets on the perimeter and a different material for the plenum. This laboratory testing was a continuation of the original perimeter slotted CAC design. Using gravimetric and instantaneous sampling of respirable dust concentrations underneath and outside of the CAC. the laboratory testing was completed using three different blower fans that delivered differing airflows. The maximum plenum airflow velocities ranged from 2.34 to 3.64 m/s (460-716 fpm). Results showed plenum respirable dust concentrations ranging from 34.6% to 49.3% lower than respirable dust concentrations outside the plenum protection zone, thus showing an improvement in protection for the roof bolter operators.

Optimization of Vehicle Side Curtain Airbag Module Based on Computer Aided Engineering

Compared with other kinds of airbags, curtain airbag（CAB） has more complex structures and larger coverage area. The product development process depends on many module tests, sled tests and full size vehicle tests. Computer aided engineering（CAE） technology can replace tests to a great extent, also save test costs and product development time. This paper introduces the way of setting up simulation models and application of static deployment tests and free motion headform（FMH） tests to verify simulation models. In the CAB simulation, uniform pressure airbag models and computational fluid dynamics（CFD） models are all used. The uniform pressure airbag models are not able to simulate the pressure difference among different parts inside the cushion during inflating process. CFD-based CAB models are used to help the curtain airbag optimization design. Based on effective CAE simulation, the optimization analyses related to diffuser tube parameters, inflator mass flow rate and cushion folding patterns are discussed and performed in different cases. The optimization result shows that the proposed techniques are helpful to the parametric optimization design of side curtain airbag module in curtain airbag development process.

Airflow characteristics by air curtain jets in full-scale room

A new air distribution pattern,air curtain jet ventilation was presented.The ventilation or airflow patterns and the air velocity produced by air curtain jet were investigated in detail.To identify the airflow characteristics of this novel air curtain jet ventilation system,a full-scale room was used to measure the jet velocity with a slot-ventilated supply device,with regards to the airflow fields along the vertical wall as well as on the horizontal floor zones.The airflow fields under three supply air velocities,1.0,1.5 and 2.0 m/s,were carried out in the full-scale room.The experimental results show the velocity profiles of air distribution,the airflow fields along the attached vertical wall and the air lake zones on the floor,respectively.The current experimental research is helpful for heating,ventilation and air conditioning(HVAC) engineers to design better air distribution in rooms.

Retention of clay-solidified grouting curtain to Cd^(2+), Pb^(2+) and Hg^(2+) in landfill of municipal solid waste

The effects of components and their ratio of grouts on anti-seepage capability of clay-solidified grouting curtain and its permeability of heavy metal cations were investigated by permeating experiments, using reactive solute transport model to study the permeation of heavy metals (Cd2+, Pb2+ and Hg2+). The study of permeating for different mixture ratios of cement and clay indicates that hydraulic conductivity of clay-solidified grouting curtain with different ratios of solid to liquid or with the same ratio of solid to liquid but with different ratios of cement to clay is changed. The laboratory simulation test results also show that precipitates produced in heavy metal cation migration process in curtain block up water flowing passage which makes the hydraulic conductivity of the solution-permeated curtain decrease with the leakage time. The permeation velocities for different heavy metal cations vary with ionic concentration, exchange capacity and ion radius etc. The test results indicate that the permeation rapidity order of heavy metals cations in clay-solidified grouting curtain is Hg2+>Pb2+ in the same experimental circumstance. In addition, permeability for different mixture ratios and antisepsis capabilities of clay-solidified grouting curtain were studied in tests.

Laboratory testing of a shuttle car canopy air curtain for respirable coal mine dust control

Canopy air curtain （CAC） technology has been developed by the National Institute for Occupational Safety and Health （NIOSH） for use on continuous miners and subsequently roof bolting machines in underground coal mines to protect operators of these machines from overexposure to respirable coal mine dust. The next logical progression is to develop a CAC for shuttle cars to protect operators from the same overexposures. NIOSH awarded a contract to Marshall University and J.H. Fletcher to develop the shuttle car CAC. NIOSH conducted laboratory testing to determine the dust control efficiency of the shuttle car CAC. Testing was conducted on two different cab configurations： a center drive similar to that on a Joy 10SC32AA cab model and an end drive similar to that on a Joy 10SC32AB cab model. Three different ventilation velocities were tested-0.61, 2.0, 4.3 rrds （120, 400, and 850 fpm）. The lowest, 0.61 m/s （120 fpm）, represented the ventilation velocity encountered during loading by the continuous miner, while the 4.3 m/s （850 fpm） velocity represented ventilation velocity airflow over the shuttle car while tramming against ventilation airflow. Test results showed an average of the dust control efficiencies ranging from 74 to 83% for 0.61 m/s （120 fpm）, 39%-43% for 2.0 m/s （400 fpm）, and 6%-16% for 4.3 m/s （850 fpm）. Incorporating an airflow spoiler to the shuttle car CAC design and placing the CAC so that it is located 22.86 cm （9 in.） forward of the operator improved the dust control efficiency to 51%-55% for 4.3 m/s （850 fpm） with minimal impact on dust control efficiencies for lower ventilation velocities. These laboratory tests demonstrate that the newly developed shuttle car CAC has the potential to successfully protect shuttle car operators from coal mine respirable dust overexposures.