Diurnal Variations in the Horizontal Temperature Distribution using the High Density Urban Climate Observation Network of Daegu in Summer

Purpose The purpose of this paper is to join a sheet of the AA7075 with the high-density polyethylene (HDPE) by a lap joint using friction spot processing and investigate the temperature distribution of joint during this process using the finite element method (FEM). Design/methodology/approach A semi-conical hole was manufactured in the AA7075 specimen and a lap joint configuration was prepared with the HDPE specimen. A rotating tool was used to generate the required heat to melt the polymer by the friction with the AA7075 specimen. The applied tool force moved the molten polymer through the hole. Four parameters were used: lower diameter of hole, rotating speed, plunging depth and time. The results of shear test were analyzed using the Taguchi method. A FEM was presented to estimate the temperature distribution of joint during the process. Findings All specimens failed by shearing the polymer at the lap joint region without dislocation. The specimens of the smallest diameter exhibited the highest shear strength at the lap joint. The maximum ranges of temperature were recorded at the contact region between the rotating tool and the AA7075 specimen. The tool plunging depth recorded the highest effect on the generated heat compared with the rotating speed and plunging time. Originality/value For the first time, the AA7075 sheet was joined with the HDPE sheet by friction spot processing. The temperature distribution of this joint was simulated using the FEM.

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Improvement in airflow and temperature distribution with an in-rack UFAD system at a high-density data center

Building and Environment ◽

10.1016/j.buildenv.2019.106495 ◽

2020 ◽

Vol 168 ◽

pp. 106495

Author(s):

Xiaolei Yuan ◽

Xinjie Xu ◽

Jinxiang Liu ◽

Yiqun Pan ◽

Risto Kosonen ◽

...

Keyword(s):

Temperature Distribution ◽

Data Center ◽

High Density ◽

Density Data

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Impacts of Urban Form on Thermal Environment Near the Surface Region at Pedestrian Height: A Case Study Based on High-Density Built-Up Areas of Nanjing City in China

Sustainability ◽

10.3390/su12051737 ◽

2020 ◽

Vol 12 (5) ◽

pp. 1737 ◽

Cited By ~ 2

Author(s):

Junyan Yang ◽

Beixiang Shi ◽

Geyang Xia ◽

Qin Xue ◽

Shi-Jie Cao

Keyword(s):

Urban Form ◽

Thermal Environment ◽

Urban Climate ◽

Urban Canopy ◽

Surface Region ◽

High Density ◽

Average Height ◽

Near Surface ◽

Building Density ◽

Thermal Environments

The continuous worsening of urban thermal environments poses a severe threat to human health and is among the main problems associated with urban climate change and sustainable development. This issue is particularly severe in high-density built-up areas. Existing studies on the thermal environments (temperature data extracted from satellite remote sensing images) are mainly focused on urban canopy areas (airspace below the average height of trees or buildings) rather than the near surface region (at pedestrian height). However, the main outdoor activity space of urban residents is the area near surface region. Hence, this study aims to investigate the influence of urban form (i.e., building density, height, and openness) on thermal environment near the surface region. The high-density built-up areas of a typical megacity (i.e., Nanjing) in China were selected, and the thermal environments of 26 typical blocks were simulated using ENVI-met software. Temperature field measurements were carried out for simulation validation. On this basis, a classified and comparative study was conducted by selecting the key spatial form elements that affect thermal environments. The results showed that in actual high-density built-up areas, single urban form parameter does not determine the thermal environments near the urban surface but mainly affected by the use (function) of space. For this study, the overall thermal environment of a street block is optimal when the building density is between 40% and 50% and the average building height is between 8 and 17 stories. Nonetheless, the urban form can be improved to optimize the overall effects on building functions and thermal environments. Furthermore, function-specific urban form optimization strategies were proposed to optimize thermal environments according to specific functional needs.

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Estimation of the energy demand for air conditioning using the outdoor temperature distribution calculated by the urban climate model.

ENVIRONMENTAL SYSTEMS RESEARCH ◽

10.2208/proer1988.27.165 ◽

1999 ◽

Vol 27 ◽

pp. 165-170

Author(s):

Takahito UENO ◽

Manabu SHIBATA ◽

Hiroki TANIKAWA ◽

Hidefumi IMURA

Keyword(s):

Temperature Distribution ◽

Energy Demand ◽

Air Conditioning ◽

Climate Model ◽

Urban Climate ◽

Outdoor Temperature

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Study of mobile measurements for detailed temperature distribution in a high-density urban area in Tokyo

Urban Climate ◽

10.1016/j.uclim.2017.06.006 ◽

2018 ◽

Vol 24 ◽

pp. 517-528 ◽

Cited By ~ 6

Author(s):

Hiroki Yokoyama ◽

Ryozo Ooka ◽

Hideki Kikumoto

Keyword(s):

Temperature Distribution ◽

Urban Area ◽

High Density ◽

Mobile Measurements

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Does “Alpine Pumping” have an effect on the ventilation of Munich?

10.5194/egusphere-egu2020-11498 ◽

2020 ◽

Author(s):

Katrin Sedlmeier ◽

Meinolf Koßmann ◽

Kristina Winderlich ◽

Maximilian Graf ◽

Gudrun Mühlbacher

Keyword(s):

Temperature Distribution ◽

Rural Areas ◽

Natural Ventilation ◽

Climate Model ◽

Regional Climate ◽

Urban Climate ◽

Wind System ◽

Maximum Heat ◽

City Area ◽

The City

Alpine Pumping refers to a thermally driven circulation between the Alps and the Alpine foreland in southeastern Germany, which occurs regularly under clear and calm weather conditions (e.g. Lugauer and Winkler (2005)). Earlier studies suggest, that the ventilation of the city of Munich, and thus the urban temperature distribution, could be influenced by this regional wind system. The present work was conducted in a cooperation framework between the city of Munich and the German Meteorological Service. The occurrence of Alpine Pumping and its effect on the temperature distribution in the city of Munich were investigated by temporary and operational wind measurements as well as numerical simulations. The thermal wind system was simulated with the regional climate model COSMO-CLM and the characteristics of Alpine Pumping deduced from this simulation used as input for the high-resolution urban climate model MUKLIMO_3. Using a radiation-based criterion, Alpine Pumping occurs on about 60 days per year, mostly in the summer months when the heat load is highest. The wind fields of temporary measurements in the rural areas south of Munich show the expected daily cycle of the wind system, especially the southerly flow during the night, which transports cold air from the mountains into the city. An influence of the regional circulation pattern on the temperature in the city area was found in a case study with the urban climate model MUKLIMO_3. Especially at night and in the morning hours, the cooler air from the surroundings ventilates the city area. Furthermore, the model results show a spatial shift of the maximum heat island in Munich during the course of the day.The findings show, that Alpine Pumping is a rather frequent phenomenon in the study area and represents an important contribution to the natural ventilation of different areas within the city.&#160;References:LUGAUER, M., WINKLER, P., 2005: Thermal circulation in South Bavaria - climatology and synoptic aspects. Meteorologische Zeitschrift. 14, 15-13.

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