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Improving air quality in occupied area has always been the core focus of ventilation design in cleanrooms. A 10,000 class pharmaceutical cleanroom, with secondary return system, was firstly introduced. Full computational fluid dynamics procedure validated by on-site measurements was then applied to model such cleanroom airflow and particle transport. Energy balance of this ventilation system was also analyzed. Details of room airflow and contaminant fields for the specific zone (above the device and around the human body) were subsequently analyzed concerning the effect of delivering ventilation flow rate and return air volume. Representative parameters, mean age of air, contaminant removal effectiveness, and air change efficiency at the occupied zone and the whole space were evaluated. Results demonstrate that promotion of the return air volume in the occupied area could appropriately reduce pollutant concentration level. Moreover, an increase in ACH (air change rate per hour) did not always shorten the local age of air near the equipment. For a large ACH, it not only will raise the dust around the machine again, it will also cause uncomfortable flow draft. Additionally, when ACH = 20 h−1 and 25 h−1 were achieved respectively, the age of air was reduced by 32% and 21.4% in the whole room and further done by 31.1% and 23.5% in the occupied zone; with identical changes, room air change efficiency (RACE) was achieved at 49.3 % and 50.4 %, respectively. It shows that the increase of ACH seems to have little effect on the air change efficiency. When ACH increases from 15 h−1 to 20 h−1, the efficiency of pollutant removal at the occupied zone will not be significantly improved ( e = 1.78).

Present work numerically and theoretically investigates the fluid flow and heat transfer in an inclined solar chimney induced by thermal buoyancy within a range of thermal Rayleigh numbers (Ra) and chimney inclination angles (α). Transport paths of fluid and heat were visualized by streamlines and heatlines, respectively. Backflow could be observed in the solar chimney when Ra increases beyond a certain value, and it directly paralyses the ventilation of the chimney. Numerical results further demonstrate that the larger the inclination angle α is, the smaller the corresponding critical Ra number of the reverse flow occurs at the glass side is. The larger the inclination angle α is, the greater Nusselt (Nu) value of the absorber wall is, while its increment rate decreases gradually with the increase of the inclination angle α, when thermal Ra is maintained. As α varies from 30° to 90°, corresponding critical Ra for reversal flows gradually decreases; furthermore, these critical values obtained by the theoretical solutions were higher than those from simulation. Volume flow rates increase positively with Ra when α is no more than 30°; however, they increase initially and then decline with Ra when α is no less than 45°. In order to enhance ventilation performance, a solar chimney flush attached with discrete heating sources on the glazing wall is proposed. The numerical results indicated that modified inclined solar chimney with discrete heating sources could enhancing its ventilation performance by preventing reverse flow occurring in the channel. Our investigations also showed that the optimal inclination angle for maximum volume flow rate heavily depends on Ra. This research could provide necessary technical support and guidance for solar energy utilization and building energy conservation through air channel in building envelopes.

Two-Phase Closed Thermosyphons (TPCTs) is a high-efficiency heat transfer technology being widely utilized in the fields of built and solar energy exploitations. In present work, a 2-D steady-state model is innovatively proposed to investigate thermal performance and flow dynamics of a single TPCT containing nanofluids. Conservation equations for mass, momentum, and energy were fully solved by the dichotomy algorithm. The effects of input powers, nanoparticles materials (Al2O3, Fe2O3 and Cu), and concentration levels (φ = 0–12 wt%) on the thermodynamics and entropy generation of the thermosyphon were numerically investigated and the results were evaluated through those from the pure water. A substantial change in the liquid film thickness, flow velocity profile, interfacial shear force, local heat transfer coefficient, temperature distribution, entropy generation rate and thermal resistance were subsequently obtained when using a nanofluid. Our numerical results revealed that nanofluids in thermosyphon could effectively enhance thermal performance by decreasing the evaporator temperature, thereby reducing overall entropy generation by about 41%, 32% and 29% for Cu, Fe2O3 and Al2O3 in comparison with pure water, respectively. Additionally, entropy generation significantly decays when nanoparticle concentration levels promote. Numerical results further indicate that the flow resistance of working fluid increases, maximum friction entropy generation increases by approximately 36.37%, 15.15%, and 9.09% for Cu, Fe2O3, Al2O3 of φ = 9 wt%, respectively. Moreover, the existence of an optimum concentration level for nanoparticles in maximizing the heat transfer limit was theoretically achieved for all nanofluids. Current results agreed well with experimental data within average deviation being no more than 10%. In conclusions, results suggest that TPCT-solar collect using nanofluid has a low simple payback period to absorb solar radiation to convert thermal energy compared to the conventional one charged with pure water.

This paper proposed one novel Thermo-Electric Ventilation (TEV) system driven by the concentrated photovoltaic-thermoelectric generator (CPV-TEG), which could use the electric power converted directly from solar energy by CPV-TEG. The effects of incident solar irradiance, number of thermoelectric generators, and ambient air temperatures on the power output of CPV-TEG have been analytically investigated through energy balance and first law of thermodynamics. Furthermore, input current and number of thermoelectric coolers were sensitively varied to optimize the performance of TEV system respectively in heating and cooling modes. Finally, an integrated theoretical and numerical approach was proposed to match the power output of CPV-TEG with the power input of TEV. Modeling results indicate that the output power from CPV-TEG could satisfy the energy demand of TEV system when the input currents of thermoelectric coolers were no more than 2.5 A and 2.8 A respectively for cooling and heating modes. Minimum energy and exergy efficiencies of the system in winter heating mode were confirmed to be 1.67 and 0.24 respectively, which were far higher than that in summer cooling mode. This research may be helpful for enhancing performance and reducing exergy destruction of thermoelectric ventilation system, simultaneously.

The interest-driven creator (IDC) theory is being developed as a group endeavor by Asian researchers to articulate a holistic learning design theory for future education in Asia. The theory hypothesizes that students, driven by interest, can be engaged in the creation of knowledge (generating ideas and artifacts). By repeating this creation process in their daily learning routines, they will excel in learning performance, develop twenty-first-century competencies, and form creation habits. We hope that with such practices in education, our future generations will ultimately become lifelong interest-driven creators. In IDC Theory, there are three anchored concepts, namely, interest, creation, and habit. Each anchored concept comprises three component concepts which form a concept loop. For example, the creation loop consists of three component concepts—imitating, combining, and staging. Imitating is concerned with taking in (or inputting) an abundant amount of existing knowledge from the outside world to form one’s background knowledge. Combining refers to delivering (or outputting) new ideas or artifacts prolifically by synthesizing existing information encountered in the world and thoughts arising from the students’ background knowledge. Staging relates to frequently demonstrating the generated ideas or artifacts to the relevant communities and receiving feedback from these communities to improve the novelty and value of the demonstrated outcomes while gaining social recognition and nurturing positive social emotions. This paper focuses on describing the three components of the creation loop. We provide three case studies to illustrate the creation loop at work, as well as how it intertwines with both the interest and habit loops in supporting students to develop their creation capabilities. In presenting this iteration of the creation concept, an anchored concept in IDC theory, we acknowledge the roles played of imitation, combination, and staging in different learning and education contexts—indeed, there are multiple theories that inform and intersect with it.

Fluid flow and heat transfer mechanism in a solar chimney induced by thermal buoyancy within a range of Ra numbers are reported by numerical and experimental investigations. The transport paths followed respectively by air and heat are visualized by streamlines and heatlines. Numerical results demonstrate that the reverse flow not only slows down the volume flow rate but also accelerates backflow presented in the solar chimney when Ra increases beyond a certain value, which makes the solar chimney lost its role of ventilation. In order to suppress the reverse flow and enhance ventilation performance, a solar chimney with multiple discrete sources flush attached the glazing wall is proposed. The effects of the sizes, positions, and numbers of those discrete heat sources on the system heat transfer rate and volume flow rate are discussed. After comparing with conventional solar chimney, the modified solar chimney with discrete heat source of height D0 = 1 and position S0 = 1 could perform better, not only preventing reverse flow but also enhancing the ventilation performance. The results obtained by the lab experimental measurements were agreed well with former numerical simulations. Temperature distributions along the heated wall for different heat input at ambient temperature illustrate the temperatures on the heated wall do not increase linearly and even drop near the top exit. This research could be significant for solar energy utilization and building energy conservation.

In order to study the influence of the ground motion spatial effect on the seismic response of large span spatial structures with isolation bearings, a single-layer cylindrical latticed shell scale model with a similarity ratio of 1/10 was constructed. An earthquake simulation shaking table test on the response under multiple-support excitations was performed with the high-position seismic isolation method using high damping rubber (HDR) bearings. Small-amplitude sinusoidal waves and seismic wave records with various spectral characteristics were applied to the model. The dynamic characteristics of the model and the seismic isolation effect on it were analyzed at varying apparent wave velocities, namely infinitely great, 1000 m/s, 500 m/s and 250 m/s. Besides, numerical simulations were carried out by Matlab software. According to the comparison results, the numerical results agreed well with the experimental data. Moreover, the results showed that the latticed shell roof exhibited a translational motion as a rigid body after the installation of the HDR bearings with a much lower natural frequency, higher damping ratio and only 1/2∼1/8 of the acceleration response peak values. Meanwhile, the structural responses and the bearing deformations at the output end of the seismic waves were greatly increased under multiple-support excitations.

In the present work, a novel heat transfer device, radial heat pipe (RHP) has been investigated due to lower flow resistance. Mathematical and computational fluid dynamics (CFD) models have been developed to investigate their thermal performance and two phases flow process inside RHP. The steady-state theoretical model of RHP has been employed to investigate the influence of various filling ratio range of (0–60%) of water and three different values of heat input (3267 W, 4004 W and 4817 W) on the thermal performance of a RHP at different operating conditions. CFD simulations further demonstrate that present built VOF model could effectively reproduce phases-change fluid flow and heat transfer inside RHP. Phenomena such as nucleation boiling, coalescence of bubbles, formation of the liquid film were observed in the heat pipe. Moreover, numerical modelling results were well validated by the experimental tests for various conditions, and maximum deviation falls within 10%.

Air conditioning and ventilation in buildings are major sources of energy consumption, particularly in large industrial buildings with significant pollutant and heat sources. Unfortunately, air flow motions in these slot-ventilated large building spaces are currently poorly understood, particularly concerning their special flow behaviours – multiple steady flows, i.e., identical boundary conditions but different initial conditions or load perturbations may lead to two or more flow solutions. Multiple steady enclosure flow behaviours essentially complicate the convective transport of air, heat and species, which has been vividly analyzed by streamlines, heatlines and masslines. In the present study, the flow mechanisms and transitions driven by combined natural and forced convections in an industrial building space for a welding process will be investigated through the numerical methodology of computational fluid dynamics. The research has taken into consideration the effects of ambient air temperature, indoor heating loads, and welding shifting position on multiple flow motions. The parameters governing the problem are the Reynolds number (103 ≤ Re ≤ 107) and the Grashof number (107 ≤ Gr ≤ 1013) and it is observed that the multiple-steady-regions can be maintained for a range of values of Gr/Re2, 150

Bullous skin disorders are induced by different pathomechanisms and several are emergent, including Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN). Rapid diagnostic methods for SJS/TEN or cytotoxic T-lymphocyte (CTL)-mediated bullous disorders are crucial for early treatment. Granulysin, primarily expressed by CTLs, is a specific cytotoxic protein responsible for SJS/TEN and similar skin reactions.To assess granulysin levels in blister fluids to differentiate SJS/TEN and similar CTL-mediated bullous reactions from other autoimmune bullous disorders.Using ELISA, we measured granulysin in blister fluids from patients with bullous skin disorders, including SJS/TEN, erythema multiforme major, bullous fixed-drug eruption, bullous lupus erythematosus, paraneoplastic pemphigus, pemphigus vulgaris, bullous pemphigoid, purpura fulminans-related bullae, and hand-foot syndrome/hand-foot-skin reactions. We compared serum and blister granulysin levels in patients with SJS/TEN presenting varying severity, monitoring serial granulysin levels from acute to late stages.Overall, 144 patients presenting with bullous skin disorders were enrolled. Blister granulysin levels (mean ± SD) in CTL-mediated disorders, including TEN (n = 28; 3938.7 ± 3475.7), SJS-TEN overlapping (n = 22; 1440.4 ± 1179.6), SJS (n = 14; 542.0 ± 503.2), erythema multiforme major (n = 7; 766.3 ± 1073.7), generalized bullous fixed-drug eruption (n = 10; 720.4 ± 858.3), and localized bullous fixed-drug eruption (n = 16; 69.0 ± 56.4), were significantly higher than in non-CTL-mediated bullous disorders (P.0001), including bullous lupus erythematosus (n = 3; 22.7 ± 20.1), paraneoplastic pemphigus (n = 3; 20.3 ± 8.6), pemphigus vulgaris (n = 3; 4.4 ± 2.8), bullous pemphigoid (n = 18; 4.0 ± 2.7), purpura fulminans (n = 4; 5.9 ± 5.5), and hand-foot syndrome/hand-foot-skin reactions (n = 6; 4.6 ± 3.5). Blister granulysin levels correlated with clinical severity of SJS/TEN (P.0001).Determination of blister granulysin levels is a noninvasive and useful tool for rapid differential diagnosis of SJS/TEN and other similar CTL-mediated bullous skin disorders for treatment selection.

In this work, a framework of charge transports in proton-conducting solid oxide fuel cells (H-SOFCs) with considering current leakage is developed by assuming four electrode reactions. Current leakage occurs when electron holes pass through the electrolyte and combine with electrons at the anode side. An analytical solution of leakage currents is proposed depending on the Nernst-Planck equation. On the basis of the analysis expression, a mathematical model of H-SOFCs is proposed, which can provide the information about current-voltage characteristics, leakage current density, Faraday and energy efficiencies. Furthermore, H-SOFCs with the BaZr0.8Y0.2O3 electrolyte are fabricated and tested, and the proposed model well reproduces the experimental data. The simulation results indicate that current leakage primarily affects the H-SOFC performance when the output voltage is close to the OCV. Both Faraday efficiencies and energy efficiencies decrease with increasing operating temperatures due to the existence of current leakage.

The turbine hall houses a number of components with intense heat release, resulting in a hot and humid air environment and making it very unpleasant for plant staffs to conduct maintenance work there, particularly at a hot outdoor environment. The traditional pure buoyancy driven natural ventilated could fulfil the overall heat exhausting requirement, however, creating hot environment at several positions due to the vortex airflow structure. As only part of the building need to be cooled, a localized cooling system with assisting mechanical fans is used. Buoyancy driven natural ventilated flows primarily occupying this turbine hall have been investigated by a computational fluid dynamics (CFD) model and an on-site measurement. The ventilation airflow is solved by 3D steady state Reynolds Averaged Navier-Stokes (RANS) equations in conjunction with the SST k-ω turbulence model. The numerical codes and procedures were validated by comparing with on-site measurements. The concept of mean age of air is used to evaluate the natural ventilated efficacy. Following that, the potential of using mechanical vents and slabs to cool equipment work area at this buoyancy driven natural ventilated hall is analysed. The simulation results show that the mechanical vents could decrease air temperature and increase air exchange efficiency at work area effectively on condition that the local airflow pattern is well organized, which is strongly related to the ejection direction and velocity. Present research could benefit future development of the ventilation design in the power plant buildings.

This paper investigates the single-sided wind driven natural ventilation with two apertures on the rear wall, regarding different horizontal aperture separations, magnitudes of incoming wind speed and various side ratios (L/D, length/width). In the present work, CFD simulations are performed with Reynolds-Averaged Navier-Stokes (RANS) approach, and pressure correction linked equation is adopted to provide closure. The simulation results indicate that wind flow behind the rear wall is essentially driven by the pumping mechanism due to vortex shedding, in which wind flow direction alternates at a mean rate. The frequency of the “pumping” flow increases dramatically with the wind flow velocity at a wide range of Reynolds numbers. The decrease of free aperture separation reduces the enclosure flow rate whilst the frequency of the wind flow almost maintains at a constant value. The increase of sidewall length has similar impacts on the ventilation frequency and the dimensionless ventilation flow rate. Numerical investigations further demonstrate that non-dimensional ventilation rate can be promoted by increasing incoming wind velocities when the wind speed is less than 5 m/s. This promotion will be restrained when the wind speed is further increased. The simulation results of built enclosure flow rate, frequency of enclosure flow can be applied to improve the ventilation performance of buildings merely with rear wall openings.

The “thermal effect” of the green roof system on the pollutant dilution process would be analyzed in this research. Different arrangement schemes (on the rooftop, windward side and leeward side) of the green roof system would alter the thermal buoyancy distribution in the street canyon, thus change the overall flow field and pollutant dilution condition Computational Fluid Dynamics (CFD) technique along with the Renormalization Group (RNG) k-e turbulence model has been adopted for the simulation work. Cases without the green roof system are assumed to be uniformly heated and are prepared for benchmark comparisons. Six aspect ratios (H/W) and ten ranks of unstable thermal stratifications (Rb) are selected to consider the influence of street canyon morphology and thermal buoyancy. Results demonstrate that the lateral deployment of green roof system performs better than the rooftop deployment and the situations without green roof system. In the windward cooling cases, a single vortex is formed in the canyon center and dramatically reduces the pollutant retention time τ when H/W > 1, while in the leeward cooling cases, a “free airflow” region is formed in all the tested aspect ratios expect for H/W = 0.5. The rooftop deployment scheme has negative effects, not just decaying ventilation performance, but also delaying pollutant dispersion period. Present research could benefit the rational design of the green roof system in the urban building clusters, and further enhance its cooling capacity for the built energy conservation.

An objective-oriented optimization procedure consisting of a simplified conjugated gradient methodology and a two-dimensional fluid and thermal energy transfer model is implemented to discover optimal morphologies of local heating elements. Direct heat transfer problem and inverse optimization problem are subsequently investigated. Full simulation shows that thermal Rayleigh number, enclosure inclination, heating strength ratio and size ratio of local heating sources have significant effects on the natural convection heat transfer in the inclined enclosure, asymptotically modeling like solar energy collectors or electronic boxes. The fluid flow and energy transfer inside the enclosure are analyzed in some representative situations, by the simultaneous use of streamlines, isotherms and heatlines. Inverse natural convection solutions on the maximization of global conductance are addressed, concerning on the effects of thermal Rayleigh number, inclination angle, heater strength ratio and heater length ratio. Mathematical correlations have been proposed by the multiple linear regressions to identify the role of governing parameters on maximizing global conductance and optimal morphologies of the discrete heat sources, concerning on the unique global heating flux. Present numerical methodology and inverse procedures could benefit free cooling of electronic components and effective solar collection elements.

Improved ventilation in an urban residential neighborhood is a determinant for better energy efficiency and air quality of the neighborhood. This is particularly important for the real estimates recently developed in many cities in China, as these neighborhoods are built with high density. In this paper, we consider in an idealized neighborhood with two categories of packaging building densities (λp) of 0.25 and 0.44, which respectively represent medium and compact urban development. For each packaging density, the frontal area density of arrays is varied from 0.125 to 0.5 through adding building blocks and reducing building size simultaneously. Computational fluid dynamics simulations are carried out to predict the wind flow through the building arrays by the use of renormalization group (RNG) k-e turbulence model. Our predictions are validated by comparing with experimental data. Numerical results reveal that ventilation rate could be greatly enhanced when a low level of packaging building density is maintained. The momentum exchange rate at the canopy roof level is effectively strengthened when the frontal area density decreases, together with a reduction of ventilation in the urban canopy layer (UCL). Additionally, a linear relationship is found between the UCL ventilation rate and the momentum exchange rate at the urban canopy roof level. For a constant packaging density, reducing frontal area density improves the city block ventilation by enhancing the air exchange rate at the roof level rather than increasing horizontal drag. This paper also illustrates a practical strategy in optimum neighborhood building layout design to minimize the pollutant level.

High-efficient evaluations of building performance are often required for comparisons of different design alternatives in architectural sustainable design processes. General Computational Fluid Dynamics (CFD) simulations are usually complicated and time-consuming for wind environment investigation and evaluation. A hybrid framework for rapid evaluation of pedestrian-level wind environment will be proposed in the present work. This framework will then be formulated by integrating parametric design, CFD simulation, image processing, and machine learning, and it could immediately predict the Low-Velocity Areas (LVAs) around rectangular-form buildings. A large amount of data of 300 building cases generated by parametric design, CFD simulation, and image processing to train a Machine Learning Model (MLM) could be applied for the prediction of LVAs. In the case investigations, MLM was tested in the prediction of the other new 24 building cases with random geometric parameters. The comparison of MLM and CFD results showed that their solutions were close to each other. Efficiency and accuracy of the hybrid framework were further demonstrated through quantitative analysis of statistical discrepancies of MLM and CFD results. Hybrid framework was an original attempt to integrate multiple emerging computational tools, and it could provide high-efficient quantitative analysis of wind environment and give practical design optimization information in the early stage.

Nowadays, the leakage model of low-pressure natural gas pipeline under the atmospheric environment has been established with the leak rate decrease with time. The Fluent software is used to simulate the concentration distribution and velocity distribution of gas among buildings at different time after the leakage, the influence of aspect ratio, distance between buildings is considered to maximally simulate the impact of external environment on natural gas leakage and diffusion. Finally we obtained the diffusion trend and concentration distribution under different conditions of gas leakage, so that rescue workers can acquire the transport status and influence of leaked gas in blocks in a short time, and provide a theory foundation for accident rescue.

The building sector accounts for significant portion of total final energy use in most countries. One way to reduce significantly building energy consumption is to adopt energy efficiency technologies and strategies. Due to environmental concerns and high cost of energy in recent years there has been a renewed interest in building energy efficiency. Passive House (PH) standard provides a cost-efficient way of minimizing energy demand of buildings in accordance with global principle of sustainability. However, it is ongoing challenge to improve building energy efficiency without compromising indoor environmental quality. The objective of this paper is to review the interactions between energy performance and indoor environment quality in buildings with PH standard, considering parametric sensitivity study including effects of diverse parameters on PH building performance. Passive House technologies including heat and cooling recovery ventilation, pre heating/cooling fresh air, pre-ventilation and passive cooling are presented considering different weather conditions. Thermal comfort represented by recommended thermal range and comfort zone and indoor air quality indicated by CO2 concentration have been numerically and experimentally analysed. The simulation and measurement results illuminate that it is possible to realize energy efficiency and favourable indoor environment in PH buildings at the same time.

This paper reports a computational fluid dynamics simulation of airflow and species dispersion inside street canyons and building blocks simultaneously. Urban thermal boundary flows could cause a profound effect on the dispersion of pollutant scalars and ventilation performance of street canyons. Nominal pollutant concentration differences between the urban street canyon and the countryside fresh air could be determined by a consideration of wind profile and ground vegetation. This study models the interaction of the fluid flow, thermal and pollutant dispersions based on the Reynolds number (Re), Grashof number (Gr) and their combinations – Archimedes number (Ar). The fluid, heat and pollutant dispersion performances were compared with the air, heat and pollutant removal efficiencies, indicated by the air change rate (ACR), heat removal rate (HRR) and pollutant removal rate (PRR). Numerical results indicate that Ar could promote fluid, heat and pollutant removals in street canyons. Transport function lines (contours of heat and mass functions) produced would illustrate the main recirculation developed inside these street canyons studied, to allow development of control strategies for dispersion of heat and pollutant species within these environments. The present work could contribute towards the understanding of the ventilation mechanism in street canyons surrounded by the residential buildings.

The opening location plays an important role of buildings’ environment and natural ventilation effectiveness. Present research investigated three categories of ventilation configurations: single-sided ventilation with an opening on the windward wall; single-sided ventilation with an opening on the leeward wall and cross ventilation with two openings. The velocity distribution and pressure distribution as well as the pressure coefficient are presented to analyze the representative fluid dynamic characteristics of these three configurations. Numerical results indicate that cross ventilation could achieve the best ventilation performance, and the situation for opening on the leeward wall is better than that on the windward wall. According to these results, the study gives some guidance for building design on natural ventilation and provides some useful ideas as well as approach and methodology for the development of energy-efficient buildings.

With the increasing refrigeration demand in medical field, a portable and non-toxic refrigeration box is proposed and developed in the present work. Regarding of operating stability and size minimization, thermoelectric cooler (TEC) does well in it compared with traditional cooler devices such as compressors and heat pipes. This paper aimed at obtaining the optimal cooling performance of the thermoelectric refrigeration box system. Three groups of experiments comprised of 17 working conditions were conducted, depending on the full scale experiments. The temperature of hot and cold sides, internal temperature of the refrigeration box, refrigeration capacity and coefficient of performance were investigated, concerning on the influences of the voltages on the TEC. Furthermore, theoretical analysis was developed to demonstrate there exists an appropriate electrical voltage range for the semiconductors, hot side fans and cold side fans, where cooling capacity and COP (coefficient and performance) could reach their optimal values. Afterwards, experimental system has sound operating status. Optimal performance of TEC will be enhanced further by our detailed numerical and experimental investigations.

A comprehensive investigation and review about the free vent boundary conditions are conducted regarding of natural convections inside an open cavity with one side horizontal opening, aiming to abandon the extended computational domain through imposing suitable pressure and momentum boundary conditions on the free ventilated ports. The main differences among Type A, Type C and Type D BCs are the definitions and assumptions on the free port boundary pressures. The physical governing equations for the present investigation are solved numerically for a wide range of thermal Rayleigh number and enclosure aspect ratio to identify the applicability of the four categories of free port boundary conditions. The simulation results show that, with the flow intensity increasing in the region near free opening, Type D BCs, Type C BCs and Type A BCs would take turns being the most effective and suitable BCs to achieve the flow solutions approaching to the reference ones. Regarding of the computational stability, authors-proposed free vent port boundary conditions (Type D BCs) achieve the best performance. In addition, it is found that enclosure ventilation rate is a more suitable and convincing criterion than heat transfer rate to validate the accuracy of the numerical methods.

IgA nephropathy (IgAN) is the most common cause of primary renal diseases worldwide, and the early secreted antigenic target of 6 (ESAT-6) which was secreted by Mycobacterium tuberculosis (MTB) may be involved in the development and progression of IgAN. This study aimed to investigate the role of ESAT-6 for early diagnosis of IgAN caused by MTB infection. From 2011 to 2014, 21 patients with renal tuberculosis (RTB), 25 with IgAN, and 46 with IgAN infected with MTB (IgAN/MTB) were enrolled. Serum levels of antibodies against Mycobacterium tuberculosis antigen 85A (Ag85A) were measured by ELISA. Urine culture and phage amplified biologically assay were performed to detect MTB. HE staining was used to observe the morphological changes in kidney tissues. Immunohistochemistry was applied to detect the expression of ESAT-6. Immunofluorescence staining was conducted to detect IgA1. Positive rates of serum anti-Ag85A antibody and urine culture for MTB were higher in the RTB and IgAN/MTB groups than those in the IgAN group. The positive rates of plaques were also higher in RTB and IgAN/MTB groups than the positive rate in the IgAN group. By contrast, the positive rate of ESAT-6 was lower in the IgAN group than that in the RTB group or the IgAN/MTB group, whereas the expression levels of IgA1 were higher in the IgAN and IgAN/MTB groups, compared with the RTB group. Our findings suggest that ESAT-6 and IgA1 may be helpful for early diagnosis of IgAN caused by MTB infection.

Song-Qing Stadium is one of the traditional buildings, and it is still in operation for Wuhan University. However, its fluid mechanical characteristic of natural ventilation has not been yet raised with any concerns. Application potentials of natural ventilation across this traditional building should be discovered. In this paper, Songqing Stadium with multiple windows is considered to investigate the wind-driven ventilation flows using computational fluid dynamics (CFD). The standard k – e turbulence model is adopted to simulate the flow fields inside and outside the building after the procedure has been validated well by former wind tunnel experimental results. Several cases with different numbers of openings are subsequently simulated, and the effects of the location and number of openings on the stadium air movement have been investigated. Numerical results indicate that the wind pressure distributions around and inside the building are almost unchangeable in the several representative cases. The magnitude of velocity components inside and around the building are larger in cross ventilation than that in single-sided ventilation. In cross ventilation condition, the pressure coefficient on the front wall is the largest in cross ventilation with apertures opened on both sides. Pressure coefficients on the windward wall increase with numbers of lateral openings. The velocity component V outside the stadium is very weak such that it could be neglected, whereas it is relatively strong inside the stadium because the pressure in the building is not uniform across the lateral direction. When lateral openings exist, volume flow rate increases and the openings on the leeward wall could entrain ambient air though the windward apertures are opened. Nevertheless, the lateral openings do not cause the increase of the magnitude of V. The present work helps architectures and engineers to understand the characteristics of natural ventilation in the traditional public buildings, and it provides theoretical approach for developing zero-energy buildings in the future.

A novel operating mode of thermoelectric module (TEM, cooling, heating, generation) is established for electronic devices cooling, based on the method of effectiveness-number of transfer units ( e - NTU ) . This work mainly focused on the effect of thermoelectric properties and the scale of extender block on cooling performance under different operating conditions in order to obtain effective cooling operating mode. Based on the TEM parameters, two sets of analytical solutions for thermoelectric cooler (TEC) are derived for the chip temperature Tj at a fixed cooling power Qc and Qc at a fixed Tj, respectively. The performance of TEC with/without scale of extender block is studied for the lowest chip temperature and maximum cooling capacity at fixed conditions. Analysis results show the thermoelectric properties and extender block are significant characteristics for different operating conditions. However, the coefficient of performance (COP) and temperature difference changed a little under given thermoelectric properties. The results indicate TEC system applied in electronic devices obtains effectively cooling module by controlling operating parameters, which do not changed with scale of extender block. The validation of the present analysis is also conducted compared with previous studies and through the infrared thermal imager.

Improving building energy efficiency and decreasing building energy consumption through monitoring of heating, ventilation and air conditioning (HVAC) and heat recovery systems are becoming increasingly significant due to global energy crisis and carbon emission. Therefore, evaluation on building energy efficiency and energy conservation is extremely necessary. In the present work, energy conservation performance of one low-energy school building will be intensively investigated based on more than three-year measurement results from the monitoring system with sensor network. Heat recovery efficiency and new energy conservation parameter were analytically modeled, taking the building mechanical ventilation network into account. Following that, building energy performance has been experimentally investigated concerning the effects of mechanical ventilation rates, outdoor temperature and the efficiency of the heat recovery facility. Subsequent energy performance analysis demonstrates that building energy demands for ventilation and winter heating could be decreased with the enhancement of heat recovery efficiency of the ventilation facility, and the energy conservation ratio of the air conditioning unit increases with the temperature of supply fresh air. Diverse situations of energy conservation ratio and heat recovery efficiency have been detailedly correlated according to measurement results.

In the present work, an open-type thermoelectric heating system with multiple channels was developed. A mathematical model of heat transfer, based on one-dimensional treatment of thermal and electric power, is conducted. The heating coefficient and production are both correlated in terms of temperature difference, thermal conductivity, electric resistance and electric current. The looped air circulation was designed to simultaneously recycle heat and enhance heater system performance. Experimental investigations were conducted to identify thermal performance of the thermoelectric heater. Effects of airflow rates through the heating side and cooling side, temperatures of heating side and cooling side on the performance were investigated. The heating coefficient was calculated upon that surface temperatures of hot and cold sides were recorded. The results show that the average heating coefficient of the thermoelectric heating system could reach to 1.3, which is greater than that of a typical electric heater with heating coefficient of less than one. The optimal isolation thickness for this thermoelectric heater, i.e., 14 mm, is confirmed by the experimental rig system. Generally, heating coefficient was found to increase first and decrease afterwards when the current was continuously increasing. Analytical and experimental results demonstrate that the optimum performance of the thermoelectric heat recovery heater strongly depends on the intensities of these operating parameters.

Heat pipes have been extensively applied in the domain of energy conversion and heat recovery application. A novel radial heat pipe with internally finned condenser has been proposed to recover waste heat from air conditioning units. Full mathematical description and computational fluid dynamics model were developed to predict the loop flow and thermal performance in a single radial heat pipe, respectively. The research focuses mainly on the effects of input power, filling ratio, pipe diameter, and velocity of the cooling water on the thermal performance and entropy generation rate of this novel heat pipe. Numerical results illustrate that average reductions in total thermal resistance with utilization of fins approximately achieved 8.69% and 14.78% for fins nf = 4 and nf = 8, respectively. Similarly, entropy generation rate shows an average decrease of 19.4% and 37.5% for identical operations. Additionally, the effect of internally finned condenser on the multiphase fluid flow has been comprehensively analyzed, including the break of the condensed film, generation of bubbles and nucleation boiling. The results further indicate that incorporation of internal fins has a significant influence on enhancing thermal homogenization and waste thermal recovery efficiency of a radial heat pipe. Case results agreed well with experimental data within average deviation being no more than 10%.

Periodic vortex shedding around a building could play an important role in wind-driven single-sided ventilation especially when two free openings are mounted on the leeward wall, in which case “pumping” flow dominates the natural ventilation. In this paper, we investigated the characteristics of vortex shedding and “pumping” flow affected by the arrangements of upstream buildings and opening area ratio of ports on the downstream target building. Computational fluid dynamics (CFD) simulations have been used to predict the instantaneous and mean flow fields. Numerical results indicate that the strength of “pumping” flow could be intensively weakened by two upstream buildings. Vortex shedding from the inner shear layers dominates the vortex shedding from the target building and constrains that from both upstream buildings except at W/B = 0.5, in which case the gap flow is weak and the St is close to that of a single building. The increase of upstream building length leads to decrease of the vortex shedding frequency at the wake of all buildings and ventilation rate of the downstream building. An increase of opening area ratio on the rear wall of the downstream building will raise the Strouhal number but have no positive correlation with ventilation rate. “Pumping” flow oscillating frequency does not have clear correlation with the ventilation rate. Our study on the wake vortex shedding flow across building clusters could benefit the future green design of urban buildings.

In order to promote the thermo-hydrodynamic performance of a single miniature loop pulsating heat pipe (PHP), the oscillatory behaviors and thermal transport capability of PHPs should be comprehensively and accurately analyzed. A novel closed PHP with periodic expansion-constriction condenser was proposed, where phase change and thermal transport processes could be reproduced by a comprehensive computational fluid dynamics (CFD) technique together with volume of fluid (VOF) methodology. Moreover, available experimental data were utilized in the validation of the model for the average deviations within 10%. Subsequently, a full numerical modeling for oscillating flows under different operating conditions was sensitively tested, varying thermal power and filling ratio, respectively from 18 W to 86 W and from 40% to 60%. Complicated fluid dynamical phenomena such as nuclear boiling, formation of slug, coalescence of vapor plug and flow patterns transformation have been analyzed inside the PHPs; CFD visualizations were also presented excellent agreements with flow behaviors from previous experimental photographs. Additionally, the effects of periodic expansion-constriction condenser on the flow regimes, pressure difference and thermal performance have been comprehensively analyzed. Numerical results demonstrate that 45% sharply increase in the thermal efficiency of the expansion condenser, and oscillation frequency of liquid/vapor slugs has been directly promoted for the constriction condenser. Present investigations could contribute to enhance overall performance of PHP, particularly employed for electronic cooling or heat recovery units.

IntroductionRestless legs syndrome (RLS) is a common neurological sensorimotor disorder among patients with end stage renal disease. This clinical trial aimed to provide evidence on the efficacy and safety of pramipexole in patients with uremic RLS receiving peritoneal dialysis (PD).Methods and analysisThis is a 12-week, multicentre, randomised, double-blind, placebo-controlled clinical trial. In total, 104 patients with uremic RLS receiving PD will be enrolled from four hospitals and randomly assigned in a 1:1 ratio to either placebo or pramipexole. We will determine the efficacy of pramipexole in the improvement of International RLS Study Group Rating Scale as the primary outcome, while responder rates for other RLS scales at week 12, change from baseline to week 12 for psychological status, sleep disorder and quality of life and blood pressure represent the secondary outcomes.Ethics and disseminationThe study was approved by the ethics committees of Peking University First Hospital, Xinqiao hospital of Army Medical University, Cangzhou Center Hospital and Peking University Shenzhen Hospital. The results will be disseminated in peer-reviewed journals.Trial registration numberNCT03817554

“Pumping” flow, which is essentially induced by the periodic vortex shedding, was observed when natural wind blows across a single building with two leeward openings. This oscillating flow has been proposed for use to improve wind ventilation of buildings with single-sided openings. Existing studies are limited to a single building block. In this study, effect of an upstream building on the “pumping” ventilation is investigated for various obstacle spacings, by Computational Fluid Dynamics (CFD) simulations. Simulation results show that vortex shedding frequencies could be affected by the non-dimensional obstacle spacing W/B (gap distance/building width), whereas non-dimensional ventilation rate of the downstream building shows a non-linear correlation with the obstacle spacing W/B. Particularly, when W/B continuously increases to 2.0, the ventilation rate reaches the level comparable to that of the isolated block case. Further results also demonstrate that the “pumping” ventilation rates are determined by a combination of mean and fluctuating pressure differences between the leeward openings. The spacing W/B = 2 is the optimal spacing for largest ventilation rate and therefore lowest building energy consumption by Heating, Ventilation and Air Conditioning (HVAC) systems. Our findings could benefit sustainable building design in dense cities.

A radar system for multiple targets 3D detection is presented. Based on FMCW radar, this paper proposes a kind of orthogonal receiving antenna array in horizontal and vertical dimensions respectively and introduces the detection method of range, velocity, azimuth and elevation 3D information. Furthermore, this paper solves the mismatching problem of the parameters in two dimensions under the situation of multiple targets using the proposed FFT-MTD-DBF method and decreases the false alarm rate. Finally, 3D detection results of multiple targets are obtained through simulation.

This study explored the potential of Second Life (SL), a popular multi-user virtual online environment, for university counseling. University students (n = 312) were asked to evaluate three counseling channels (i.e., traditional face-to-face, internet, and SL) based on a range of media features deemed relevant and important to counseling and to assess their relative preferability when faced with different counseling problems. For the purposes of this study, counseling rooms with different styles were built, virtual counselors with different genders, ages, and styles were created, and short video recordings of scripted counseling sessions were produced in SL. For the media feature comparisons, the collected data were analyzed by the multivariate analysis of variance, followed by the analysis of variance and post hoc comparisons when significant differences were found, whereas for counseling problem comparisons, repeated-measure analysis of variance and post hoc comparisons were used. The results for the media feature comparisons showed that SL counseling significantly out-rated traditional counseling in all of the examined media features, with the exception of the interactivity dimension. Additionally, while SL and internet counseling were both perceived as significantly better than traditional counseling in areas that are unique to computer-mediated communications, including anonymity, convenience, and flexibility with regard to time and space, as well as privacy of the counseling site, SL was perceived as distinctly superior to internet counseling in five areas due to its unique affordances, including the choice of appearance, choice of counselors, interactivity, diversity of counseling sites, and availability of counseling object dimensions. Furthermore, traditional counseling was regarded as better able to support more fluent and versatile interaction between the counselor and client than the other two computer-mediated channels. As for the results of counseling problem comparisons, SL was rated as least preferred for six out of the seven counseling problems (except for gender identity issues), despite its media affordances. Suggestions for practitioners and future research are provided based on the current findings. Electronic supplementary material The online version of this article (10.1186/s41039-017-0064-6) contains supplementary material, which is available to authorized users.

To investigate the predictive value of the acute physiology and chronic health evaluation 2 (APACHE2) score and lung injury prediction score (LIPS) for acute respiratory distress syndrome (ARDS) when combined with biomarkers for this condition in patients with ARDS risk factors. In total, 158 Han Chinese patients with ARDS risk factors were recruited from the Respiratory and Emergency Intensive Care Units. The LIPS, APACHE2 score, primary diagnosis at admission, and ARDS risk factors were determined within 6 h of admission, and PaO2/FiO2 was determined on the day of admission. Blood was collected within 24 h of admission for the measurement of angiopoietin-2 (ANG-2), sE-selectin, interleukin-6 (IL-6), and interleukin-8 (IL-8) levels. ARDS was monitored for the next 7 days. Univariate and multivariate analyses and receiver operating characteristic (ROC) analyses were employed to construct a model for ARDS prediction. Forty-eight patients developed ARDS within 7 days of admission. Plasma ANG-2 level, sE-selectin level, LIPS, and APACHE2 score in ARDS patients were significantly higher than those in non-ARDS patients. ANG-2 level, LIPS, and APACHE2 score were correlated with ARDS (P<0.001, P<0.006, and P<0.042, resp.). When the APACHE2 score was used in combination with the LIPS and ANG-2 level to predict ARDS, the area under the ROC curve (AUC) was not significantly increased. Compared to LIPS or ANG-2 alone, LIPS in combination with ANG-2 had significantly increased positive predictive value (PPV) and AUC for the prediction of ARDS. In conclusion, plasma ANG-2 level, LIPS, and APACHE2 score are correlated with ARDS. Combined LIPS and ANG-2 level displays favorable sensitivity, specificity, and AUC for the prediction of ARDS.

Decreasing the building energy consumption and improving thermal comfort through optimization of heating, ventilation and air conditioning (HVAC) control systems are becoming increasingly significant due to global energy crisis, carbon emission and requirement of high life quality for people. Therefore, evaluation on building energy efficiency and human thermal comfort is extremely necessary. In the present work, energy conservation performance of one passive school building and classroom thermal comfort enhancement will be simultaneously investigated. Energy performance of single reference classroom under six design points and whole school building with two scenarios have been numerically investigated concerning the effects of different indoor set-point temperatures, pre-ventilation, sun-shading system, and the efficiency of the heat recovery facility. Numerical results demonstrate that heating and cooling demands heavily depend on indoor set-point temperature, occupancy and heat recovery rate. Building energy performance analysis illuminates that the optimized control systems for HVAC and sun-shading systems show an expectedly energy efficient performance. In addition, classroom thermal comfort indicated by the recommended thermal range and comfort zone has been numerically and experimentally presented.

A finite element method (FEM), which implements ANSYS to analyze the performance of concrete-filled steel tubular (CFST) latticed column with initial stress, was presented. Studies showed that the FEM results agreed well with the test results. The full loading process of the CFST latticed column subjected to axial load was analyzed by combining FEM with two parameters of initial stress degree and slenderness ratio. Research results indicated that the initial stress in the steel tube of the CFST latticed column advances and elongates the elastic-plastic phase of the specimens and postpones the occurrence of ultimate load bearing capacity and relevant displacement. Furthermore, the ultimate load exhibits a significant decrease of up to 12% for long columns with large ISD, but not for short columns.