Side Of Roof Research Articles

Numerical and experimental studies on the airflow around the low-rise flat-roof buildings with different stable snowdrifts

In this study, the airflow characteristics around an isolated flat-roof building with different stable snowdrifts were investigated by adopting the Particle-Image-Velocimetry (PIV) wind tunnel experiments and Large-Eddy Simulations. First, the geometric model to be tested was obtained using a 3D printing technique, where the snowdrift pattern on the roof was provided by the results of previous wind tunnel tests conducted by the authors. Second, PIV wind tunnel experiments were carried out to measure flow information on the middle plane of the tested models (with or without snow cover). The specific physical variables (such as mean wind velocity, turbulence kinetic energy (TKE)) was then systematically analysed, which will be an important validation database to verify the LES method. Finally, the effects of the snowdrift on the time-averaged flow field, the turbulence flow field, and the wind load force acting on the buildings were discussed in detail using the LES method. The relevant research results indicate that the existence of snowdrifts changed the geometrical aerodynamic characteristics of the original roof, rendering the shape more streamlined. Thus, it significantly accelerated the passing velocity of the incoming flow over the roof, which results in the decreasing magnitudes of time-averaged Reynold stresses in the flow field above the roof. Additionally, the existence of snowdrifts can effectively restrain the size of the separation bubbles in the separating-reattachment flow field, which leads to vortices of smaller size and higher frequency being formed on the roof. Furthermore, the mean and fluctuations of wind pressure on the windward side of snowdrifts roof have larger magnitude than a roof without snow, which may increase the risk of damage to local enclosure structures near the windward side of the roof.

Multi-factor analysis on thermal comfort and energy saving potential for PCM-integrated buildings in summer

The multi-factor orthogonal simulation analysis was initiated to investigate the influence degree of four key parameters of PCM-integrated building envelopes on energy consumption and indoor thermal comfort under Chinese climate. The sensitivity and the interaction between four key parameters on energy saving and indoor temperature were discussed. The results showed that: 1) According to the influence degree on energy consumption and indoor thermal comfort time, the four key parameters of PCM envelope can be ranked in descending order as follows: envelope type > PCM layer layout > PCM type > PCM layer thickness. 2) The optimal level of all the cases studied is using BioPCMTM23 (PCM2) with a thickness of 7 cm on the inner side of both wall and roof. 3) Integrating the PCM to the envelope can effectively reduce the indoor temperature fluctuation. Considerable energy saving effects (the energy saving rate is 4.8% – 34.8%) can be achieved by properly selecting the PCMs according to local climatic conditions. The PCMs with high latent heat should be selected and placed in an envelope structure that receives longtime solar radiation and has a large surface area, which can maximize the effect of energy saving and temperature control.

Study on the Failure Mechanism for Coal Roadway Stability in Jointed Rock Mass Due to the Excavation Unloading Effect

Aiming at the large deformation instability problem caused by the excavation unloading of a coal roadway in deep-buried slowly inclined jointed rock mass, the geomechanical parameters and deformation failure characteristics of an engineering geomechanical model were investigated. The in-situ stress state of the model was measured with the stress relief method. The geological and mechanical properties of roadway surrounding rock were described. The surrounding rock structure was revealed with the electron microscopy scanning method, micro-fractures and randomly distributed joints highly developed in roadway surrounding rock. Field investigation and monitoring indicated the cross-section of roadway surrounding rock shrank continuously and the deformation distribution was obviously asymmetric. Shotcrete spalling and cable broken failures frequently occurred in the middle and ride side of roof and right rib. Based on the geomechanical conditions of the coal roadway, a discrete element numerical model of coal roadway in gently inclined jointed rock mass was established. The parameters of rock mass in the numerical model were calibrated. The model ran in unsupported condition to restore the evolution process of stress, crack propagation and deformation in roadway surrounding rock due to gradual deviatoric stress release caused by excavation. On this basis, the space-time evolution characteristics and law of stress, crack propagation and deformation were obtained and then the asymmetric large fragmentation and dilatation deformation failure mechanism of roadway surrounding rock in deep-buried slowly inclined jointed rock mass was revealed. The failure reasons of the support structure were analyzed, and the relevant support principles were proposed. The research results can provide scientific references for the stability control of roadways excavated in jointed rock mass.

Numerical Simulation of Thermal Comfort Performance in a Room with Different Insulating Materials Using Computational Fluid Dynamics<sup></sup>

Numerical simulation studies are carried out for improvement of energy efficiency in a room by with different thermal insulating materials using computational fluid dynamics (CFD). The study considered various building insulating materials (BIM’s) such as: (a) Expanded Polystyrene (EPS) (b) Fiber Glass (Resin bonded (RB)-Glass wool) (c) Polyurethane Foam (PUF) and (d) Cement Plaster (CP) along with composite bricklayer combination. A multi-physical 3D model room of size 2.6 m × 2.6 m × 2.6 m is created to analyze the performance of different insulating materials using CFD simulations. The experimental data of 24 hr temperature cycle of the ambient air is used for the analysis of performance of thermal comfort inside the room with the incorporation of different thickness of the insulating materials. The thickness of insulation 0.03, 0.1, 0.2 and 0.3 m is applied on interior side of walls and roof of the building. The study performed with different grid sensitiveness for coarse, medium and fine meshes for the improvement in the accuracy of the results. The fine grid mesh analysis is chosen to carry the further studies to compare the insulated and non-insulated condition for the thermal behavior inside the room. The result shows that the thermal conductivity and heat capacity of insulated walls are very important to be taken into account for carrying out detailed thermal analysis of buildings. The studies are carried out using commercial CFD tool of ANSYS CFX 15.0. The results of comparison shows that it is possible to maintain needed thermal comfort conditions in the room while reducing the total energy consumptions at the same time by appropriate use of BIM’s.

Characteristics of in situ stress field at Qingshui coal mine

In this study, the characteristics of geological structure at Qingshui coal mine were analyzed. And the hollow inclusion strain cell overcoring method was used to obtain the in situ stress. The effect of in situ stress on the stability of soft rock roadway was analyzed. The results show that the maximum principal stress is in the horizontal direction with a northeast orientation and has a value of about 1.2–1.9 times larger than gravity; the right side of roadway roof and floor is easily subject to serious deformation and failure, and the in situ stress is found to be a major factor. This paper presents important information for developing countermeasures against the large deformation of the soft rock roadway at Qingshui coal mine.

C111 鋼板屋根裏面からの熱放射低減による室温上昇抑制方法(OS-06:ふく射輸送制御(1))

C111 鋼板屋根裏面からの熱放射低減による室温上昇抑制方法(OS-06:ふく射輸送制御(1))

Performance study of spot cooling of tractor cabinet

Abstract The target of this research is to study theoretically and experimentally the performance of spot cooling of a tractor cabinet including a single internal heat source (tested body) by using vortex tube. In the theoretical study, the cabinet is cooled from the roof by one port while the lower and side walls temperature is kept constant. The effect of inlet and outlet air ports positions in the cabinet is considered. Moreover, we study the influence of varying some parameters as velocity and temperature of inlet cold air to the cabinet, the pressure of inlet air to the vortex tube and the cold fraction of the vortex tube in the presence of a heat source with a constant heat flux of 120 W/m2. In this work, FLUENT 6.3.26 package is used in the numerical study. The steady of the 2-D incompressible viscous flow problem is solved by using the fluent package. Various spot cooling geometries are applied. Specific conditions for each case are defined, and the computational fluid dynamics is provided for three different groups containing twelve cases of local inlet and outlet ports. The calculations are performed for ventilation effectiveness factor (VEF) which is ranging from 0.58 to 1.29. The best position for the inlet locations in this study is found in upper right side of roof and the outlet locations in upper left side of cabinet. To validate the numerical model, an experimental test rig has been designed and constructed with the actual dimensions of a tractor cabinet. The experiments are carried out with the same conditions of the ideal case. The comparison of the experimental data, for that of best position of the inlet port, with the theoretical results gives a satisfactory agreement.

THE RELATION BETWEEN THE SPREAD PAN TILES ROOFING AND THE DECREASE OF UDATSU ON TOWN HOUSE IN KYOTO

The purpose of this paper is to examine the relation between the spread of pan tiles “sangawara and hongawara” roofing and the decrease of Udatsu (high walls on the both side of gable roof) on town house in Kyoto.As the result of that, resent observation about “rakuchu-rakugaizu” folding screens have thrown light upon that pan tiles were too much heavy for Udatsu, so that Udatsu had decreased in 17th century, and 18th century again.

18〜19世紀の京都の町並景観と瓦葺規制 : 江戸時代の京都の町並景観の研究(その2)

This study aims to clarify the details of uniform townscape in Kyoto city under the Tokugawa regime. This paper deals with relation between townscape and the roofing clay tile regulation of Kyoto. As the result of that, official notices notified by Tokugawa shogunate and machibugyosho (magistrate of Kyoto) permit in the use of roofing clay tile in 1720. But the actual occurrence is that roofing clay tile has come into wide use in the 18〜19^<th> century. After that, tile roofed townscape uniformed. On the other hand, Udatsu (high walls on the both side of gable roof) has decreased.

Special Issue on rock stress estimation

In this study, the characteristics of geological structure at Qingshui coal mine were analyzed. And the hollow inclusion strain cell overcoring method was used to obtain the in situ stress. The effect of in situ stress on the stability of soft rock roadway was analyzed. The results show that the maximum principal stress is in the horizontal direction with a northeast orientation and has a value of about 1.2–1.9 times larger than gravity; the right side of roadway roof and floor is easily subject to serious deformation and failure, and the in situ stress is found to be a major factor. This paper presents important information for developing countermeasures against the large deformation of the soft rock roadway at Qingshui coal mine.

中国江南庭園におけるバショウ類（Ｍｕｓａ ｓｐｐ．）の植栽利用

This paper involves the planting design and using of Musa spp., an important and a special plant for Chinese gardens. Through literature studying and observation on gardens of Suzhou, the major results of the findings are: (1) It began from at least 2100 years ago to plant Musa spp. in imperial gardens in the Han Dynasty (B.C.206-A.D.220). Then, this plant was being used in imperial and private gardens from the Jin Dynasty (255-420). (2) Musa spp. not only have special tree-form, fresh and green stems and leave, but also can demonstrate the landscape in tropical subtropical land rather than Cycas revolute and Trachycarpus spp., etc. And Chinese cultured people like enjoying the sound beat by rain, the form swung by wind and the shadow by sunlight in day and by moonlight in night. (3) The typical methods of planting design were usually planting Musa spp. together with strange rocks, with Firmiana platanifolia, with bamboo, etc. (4) The places planting Musa spp. were inside the gardent’s doors, near the front of windows, under the side of roof and corridor, near the railing, near the steps and near the stream, etc.

九州地域に設置された住宅用太陽光発電システムの計測・解析結果 : 太陽光発電システムの住宅への応用に関する研究 その3

This paper presents the results of survey on 276 grid-connected PV generation systems and measurement of 7 systems in Kyushu area. The electricity generated for a year was in average 925.9kWh/kWp/year. It was found that the system with panels on one side of roof generates more electricity than the system with panels on plural side of roof. The electricity generated by the system with panels on one side of roof was approximately 10% more than that with panels on three sides of roofs. The amount of electricity generation from PV system is in general affected by the local solar radiation condition and the system efficiency. The relation between decrease in power generation and the shadow on the panel or the unbalanced solar radiation between panels was simulated using the data acquired by the experiment.

Ultrastructure of the osphradium of the Tertiary relict snail, Campanile symbolicum Iredale (Mollusca, Streptoneura)

The osphradium of Campanile symbolicum Iredale, 1917 is a gill-like, bipectinate sense organ, which is located at the left side of the mantle roof. The mass of the deeply clefted sensory epithelium of the leaflets is built up by sensory cells, which are provided with deeply invaginated aberrant cilia and large cytosomes containing pigment formations. In addition, many free nerve processes are present, bearing a single or few sensory cilia with accessory centrioles. Polyciliary cells are interspersed. A cell type with netlike or concentrically arranged smooth endoplasmic reticulum is commonly found near the central axis of the osphradium . The central zone of each leaflet includes nervous tissue and a complicated muscular grid, with pore cells and fibroblasts also present. Based on the fine-structural data the functional and ecological significance of the osphradium of Campanile symbolicum is discussed. The com bination of herbivory and a lamellar osphradium is rare among the Gastropoda, suggesting that the osphradium of Campanile might also be involved in reproductive biology. Many fine-structural features of the osphradium of Campanile symbolicum are unique among the gastropods and reflect the phylogenetic isolation of this relict snail. The net-like cell type, however, is probably homologous with the so-called Si4 cell in the rem aining caenogastropods, for which a largely different osphradial fine-structure is diagnostic. The affinities of Campanile symbolicum are probably closer to the Caenogastropoda than to the Allogastropoda and Euthyneura. With present knowledge it might be best classified near the base or even as the first clade within the Caenogastropoda.