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Yang, Bin
Publications (10 of 75) Show all publications
Cheng, X., Yang, B., Liu, G., Olofsson, T. & Li, H. (2018). A total bounded variation approach to low visibility estimation on expressways. Sensors, 18(2), Article ID 392.
Open this publication in new window or tab >>A total bounded variation approach to low visibility estimation on expressways
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2018 (English)In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 18, no 2, article id 392Article in journal, Editorial material (Refereed) Published
Abstract [en]

Low visibility on expressways caused by heavy fog and haze is a main reason for traffic accidents. Real-time estimation of atmospheric visibility is an effective way to reduce traffic accident rates. With the development of computer technology, estimating atmospheric visibility via computer vision becomes a research focus. However, the estimation accuracy should be enhanced since fog and haze are complex and time-varying. In this paper, a total bounded variation (TBV) approach to estimate low visibility (less than 300 m) is introduced. Surveillance images of fog and haze are processed as blurred images (pseudo-blurred images), while the surveillance images at selected road points on sunny days are handled as clear images, when considering fog and haze as noise superimposed on the clear images. By combining image spectrum and TBV, the features of foggy and hazy images can be extracted. The extraction results are compared with features of images on sunny days. Firstly, the low visibility surveillance images can be filtered out according to spectrum features of foggy and hazy images. For foggy and hazy images with visibility less than 300 m, the high-frequency coefficient ratio of Fourier (discrete cosine) transform is less than 20%, while the low-frequency coefficient ratio is between 100% and 120%. Secondly, the relationship between TBV and real visibility is established based on machine learning and piecewise stationary time series analysis. The established piecewise function can be used for visibility estimation. Finally, the visibility estimation approach proposed is validated based on real surveillance video data. The validation results are compared with the results of image contrast model. Besides, the big video data are collected from the Tongqi expressway, Jiangsu, China. A total of 1,782,000 frames were used and the relative errors of the approach proposed are less than 10%.

Place, publisher, year, edition, pages
MDPI, 2018
Keywords
total bounded variation, image spectrum, low visibility estimation, piece stationary, fog and haze
National Category
Environmental Analysis and Construction Information Technology Remote Sensing
Identifiers
urn:nbn:se:umu:diva-144176 (URN)10.3390/s18020392 (DOI)000427544000075 ()29382181 (PubMedID)
Available from: 2018-01-24 Created: 2018-01-24 Last updated: 2018-06-09Bibliographically approved
Cheng, X., Yang, B., Liu, G., Olofsson, T. & Li, H. (2018). A variational approach to atmospheric visibility estimation in the weather of fog and haze. Sustainable cities and society, 39, 215-224
Open this publication in new window or tab >>A variational approach to atmospheric visibility estimation in the weather of fog and haze
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2018 (English)In: Sustainable cities and society, ISSN 2210-6707, Vol. 39, p. 215-224Article in journal (Refereed) Published
Abstract [en]

Real-time atmospheric visibility estimation in foggy and hazy weather plays a crucial role in ensuring traffic safety. Overcoming the inherent drawbacks with traditional optical estimation methods, like limited sampling volume and high cost, vision-based approaches have received much more attention in recent research on atmospheric visibility estimation. Based on the classical Koschmieder's formula, atmospheric visibility estimation is carried out by extracting an inherent extinction coefficient. In this paper we present a variational framework to handle the nature of time-varying extinction coefficient and develop a novel algorithm of extracting the extinction coefficient through a piecewise functional fitting of observed luminance curves. The developed algorithm is validated and evaluated with a big database of road traffic video from Tongqi expressway (in China). The test results are very encouraging and show that the proposed algorithm could achieve an estimation error rate of 10%. More significantly, it is the first time that the effectiveness of Koschmieder's formula in atmospheric visibility estimation was validated with a big dataset, which contains more than two million luminance curves extracted from real-world traffic video surveillance data.

Keywords
Atmospheric visibility estimation, Variational approach, Piecewise stationary time series, Computer vision, Fog and haze
National Category
Other Environmental Engineering
Identifiers
urn:nbn:se:umu:diva-144561 (URN)10.1016/j.scs.2018.02.001 (DOI)000433169800020 ()
Available from: 2018-02-06 Created: 2018-02-06 Last updated: 2018-09-05Bibliographically approved
Yang, B., Lin, Z. & Li, A. (2018). Advanced ventilation systems − theory, practice, limitations and solutions (Editorial). Trends in Civil Engineering and Material Science
Open this publication in new window or tab >>Advanced ventilation systems − theory, practice, limitations and solutions (Editorial)
2018 (English)In: Trends in Civil Engineering and Material ScienceArticle in journal, Editorial material (Refereed) Published
National Category
Building Technologies
Identifiers
urn:nbn:se:umu:diva-144300 (URN)
Available from: 2018-01-30 Created: 2018-01-30 Last updated: 2018-06-09
Dong, J., Zhang, L., Deng, S., Yang, B. & Huang, S. (2018). An experimental study on a novel radiant-convective heating system based on air source heat pump. Energy and Buildings, 158, 812-821
Open this publication in new window or tab >>An experimental study on a novel radiant-convective heating system based on air source heat pump
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2018 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 158, p. 812-821Article in journal (Refereed) Published
Abstract [en]

Air source heat pump (ASHP) has been widely applied to many parts of the world due to its simple structure and low initial cost. To save energy consumed for spacing heating and enhance the indoor thermal environment, improving the performances of ASHP has become one of the research focus in the relevant field. Currently, the most conventional heating terminal of ASHP system for spacing heating is finned tube heat exchanger coupled with air fan, which may cause strong draught sensation and dry eye problem and make users feel uncomfortable during convective heating. On the other hand, radiant heating is attracting more and more attention due to its comfortable indoor thermal environment. In this paper, a novel radiant-convective heating terminal was presented and coupled into an ASHP system. Both the operating characteristics and heating performances of the novel system were experimentally investigated. The experimental results showed that the novel system took about 28 min to enter a steady operating stage, during which the radiant panel surface temperature and outlet air temperature for the novel heating terminal, and COP of the novel system were 40.9 degrees C, 32.1 degrees C, and 3.11, respectively, under a standard heating condition. In addition, all parameters mentioned above saw a linear increase when the outdoor air temperature increased from -4.0 to 10.0 degrees C, and their respective rising rates were 0.41 degrees C, 0.28 degrees C and 0.04 per increased outdoor air temperature. Furthermore, the experimental results also demonstrated that adjusting the indoor air flow rate could effectively allocate the amount of heat generated by different heat transfer modes, which may have significant effects on the indoor thermal environment.

Keywords
Experimental study, Radiant heating, Convective heating, Air source heat pump
National Category
Civil Engineering Building Technologies
Identifiers
urn:nbn:se:umu:diva-141055 (URN)10.1016/j.enbuild.2017.10.065 (DOI)000423636600069 ()
Available from: 2017-10-23 Created: 2017-10-23 Last updated: 2018-06-09Bibliographically approved
Cheng, X., Yang, B., Liu, G., Olofsson, T. & Li, H. (2018). Atmospheric visibility detection based on total variation and piecewise stationary time series for fog and haze weather. Sustainable cities and society
Open this publication in new window or tab >>Atmospheric visibility detection based on total variation and piecewise stationary time series for fog and haze weather
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2018 (English)In: Sustainable cities and society, ISSN 2210-6707Article in journal, Editorial material (Refereed) Published
National Category
Building Technologies
Identifiers
urn:nbn:se:umu:diva-144382 (URN)
Available from: 2018-02-01 Created: 2018-02-01 Last updated: 2018-06-09
Kabanshi, A., Ameen, A., Hayati, A. & Yang, B. (2018). Cooling energy simulation and analysis of an intermittent ventilation strategy under different climates. Energy Journal, 156, 84-94
Open this publication in new window or tab >>Cooling energy simulation and analysis of an intermittent ventilation strategy under different climates
2018 (English)In: Energy Journal, ISSN 0195-6574, E-ISSN 1944-9089, Vol. 156, p. 84-94Article in journal (Refereed) Published
Abstract [en]

Energy use on heating, ventilation and air conditioning (HVAC) accounts for about 50% of building energy use. To have a sustainable built environment, energy efficient ventilation systems that deliver good indoor environmental quality are needed. This study evaluates the cooling energy saving potential of a newly proposed ventilation system called Intermittent Air Jet Strategy (IAJS) and compares its performance against a mixing ventilation (MV) system in a classroom located in three cities with different climates, Singapore with 'hot and humid', Ahvaz with 'hot and dry' and Lisbon with "moderate" climate. The results show a significant reduction of cooling energy need and flexibility in control strategies with IAJS as a primary system in hot and humid climates like Singapore. Hot and dry climate with short cool periods like Ahvaz show possible application and considerable energy savings with IAJS as a primary system under optimized variable setpoints, but moderate climates have an increased risk of occupant discomfort likely due to increased draft especially during the cool season. Thus, IAJS as a secondary system that operates only during cooling season may be conducive for moderate climates like Lisbon. Additionally, the results show that supply fan energy savings can also be realised if well implemented.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Intermittent air jets,  IDA-ICE simulation,  Energy savings,  Convective cooling,  Hot and humid climate,  Hot and dry climate,  Moderate climate
National Category
Building Technologies
Identifiers
urn:nbn:se:umu:diva-147714 (URN)10.1016/j.energy.2018.05.093 (DOI)000437073600008 ()2-s2.0-85048207413 (Scopus ID)
Available from: 2018-05-15 Created: 2018-05-15 Last updated: 2018-08-28Bibliographically approved
Cheng, Y., Yang, B., Lin, Z., Yang, J., Jia, J. & Du, Z. (2018). Cooling load calculation methods in spaces with stratified air: a brief review and numerical investigation. Energy and Buildings, 165, 47-55
Open this publication in new window or tab >>Cooling load calculation methods in spaces with stratified air: a brief review and numerical investigation
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2018 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 165, p. 47-55Article, review/survey (Refereed) Published
Abstract [en]

Due to vertically thermal stratification in indoor spaces, the cooling load calculation is always a challenge in the design of stratified air distribution systems (STRAD), which in turn is crucial to determine the supply air flow rate and the cooling load to be removed by the air conditioning system. In this paper, several cooling load calculation methods, developed in the past 20 years and focused on STRAD systems, were briefly reviewed. It attempts to clarify these methods in terms of their advantages, limitations and suitable ranges of applications. Furthermore, series of numerical simulations with a total number of 56 cases were conducted, and the applications of a novel cooling load calculation method in STRAD systems were investigated. The reliability of the method was validated for STRAD systems with separated locations of return and exhaust grilles, when adopted in three typical spaces with different building heights, namely a small office, a large terraced classroom and a terminal building. Databases of effective cooling load factors (ECLF;) for different heat sources distributed in the three spaces were obtained and presented, which can be conveniently used to calculate cooling loads. In addition, the influences of return grill height on the occupied zone cooling load as well as the energy saving potentials of STRAD systems were also clarified. The results presented in this paper are helpful for the design and optimization of STRAD systems.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Building Technologies
Identifiers
urn:nbn:se:umu:diva-143910 (URN)10.1016/j.enbuild.2018.01.043 (DOI)000428491200005 ()
Available from: 2018-01-14 Created: 2018-01-14 Last updated: 2018-06-09Bibliographically approved
Yang, B., Olofsson, T., Wang, F. & Lu, W. (2018). Thermal comfort in primary school classrooms: A case study under subarctic climate area of Sweden. Building and Environment, 135, 237-245
Open this publication in new window or tab >>Thermal comfort in primary school classrooms: A case study under subarctic climate area of Sweden
2018 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 135, p. 237-245Article in journal (Refereed) Published
Abstract [en]

Limited studies were focused on primary school buildings especially under subarctic climate. Thermal comfort of children was assumed to be similar as that of adults, which may cause inaccuracy. To fill data blank and enrich global database, a field study was performed from late fall 2016 to early spring 2017 covering whole heating period in north part of Sweden. Indoor CO2 concentration was continuously monitored to evaluate indoor ventilation. Thermal comfort related parameters were continuously measured and predicted mean vote (PMV) was calculated. Subjective questionnaire surveys were performed every week except holidays. Subjective thermal sensation value (TSV) was always higher than objective PMV, which reflected thermal adaptation. The thermal adaptation became not obvious in middle and late winter because of long term exposure to heating environments. Heating system should be intensified gradually in early heating period, operated based on actual outdoor climate instead of experience in middle and late heating periods, extended under part load operation in early spring if necessary. The new 13-point TSV scale was pointed out by other researchers and tested inthis study, which can explore tiny TSV deviations from thermally neutral status and reflect more accurate thermal sensations.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Thermal comfort, Primary school, Subarctic climate, 13-value comfort scale, Indoor environment
National Category
Building Technologies
Identifiers
urn:nbn:se:umu:diva-145744 (URN)10.1016/j.buildenv.2018.03.019 (DOI)000430784300020 ()
Available from: 2018-03-16 Created: 2018-03-16 Last updated: 2018-06-27Bibliographically approved
Cheng, X., Yang, B., Olofsson, T., Liu, G. & Li, H. (2017). A pilot study of online non-invasive measuring technology based on video magnification to determine skin temperature. Building and Environment, 121, 1-10
Open this publication in new window or tab >>A pilot study of online non-invasive measuring technology based on video magnification to determine skin temperature
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2017 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 121, p. 1-10Article in journal, Editorial material (Refereed) Published
Abstract [en]

Much attention was paid on human centered design strategies for environmental control systems of indoor built environments. The goal is to achieve thermally comfortable, healthy and safe working or living environments in energy efficient manners. Normally building Heating, Ventilation and Air Conditioning (HVAC) systems have fixed operating settings, which can't satisfy human thermal comfort requirements under transient and non-uniform indoor thermal environments. Therefore, human thermal physiology signal such as skin temperature, which can reflect human body thermal sensation, has to be measured over time. Several trials have been performed by minimizing measuring sensors such as i-Button and mounting measuring sensors into wearable devices such as glasses. Infrared thermography technology has also been tried to achieve non-invasive measurements. However, it would be much more convenient and feasible if normal computer camera could record images, which could be used to obtain human thermal physiology signals. In this study, skin temperature of hand back, which has a high density of blood vessels and is normally not covered by clothing, was measured by i-button sensors. Images recorded by normal camera were amplified to analyzing skin temperature variation, which are impossible to see with naked eyes. The agreement between i-button sensor measuring results and image magnification results demonstrated the possibility of non-invasive measuring technology by image magnification. Partly personalized saturation-temperature model (T = 96.5 × S + bi) can be used to predict skin temperatures for young East Asia females.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Thermal sensation, Skin temperature, Video magnification, Online non-invasive, measurement
National Category
Building Technologies
Identifiers
urn:nbn:se:umu:diva-134857 (URN)10.1016/j.buildenv.2017.05.021 (DOI)000404314700001 ()
Available from: 2017-05-13 Created: 2017-05-13 Last updated: 2018-06-09Bibliographically approved
Yang, B. & Olofsson, T. (2017). A questionnaire survey on sleeping environment conditioned by different cooling modes in multistory residential buildings of Singapore. Indoor + Built Environment, 26(1), 21-31
Open this publication in new window or tab >>A questionnaire survey on sleeping environment conditioned by different cooling modes in multistory residential buildings of Singapore
2017 (English)In: Indoor + Built Environment, ISSN 1420-326X, E-ISSN 1423-0070, Vol. 26, no 1, p. 21-31Article in journal (Refereed) Published
Abstract [en]

A good sleep environment is essential to maintain a person's health and daily working performance. How to create comfortable and healthy sleep environments with less energy use is worth exploring. Findings, based on one questionnaire survey on sleep environments conditioned by different cooling modes have been reported. The study investigated the use of different cooling devices in relation to the effect on sleep. Human responses to thermal environments and air quality created by different cooling modes were also studied. Totally 229 completed questionnaires were statistically analysed. The results show that most of the respondents prefer to use air conditioner 3–6 months in a year with relatively low temperature settings especially for respondents living below fifth floor. It is better to choose relatively high temperature settings to reduce air conditioning intensity especially for elders and outdoor workers, which can not only avoid cold thermal discomfort but also reduce electric energy use. For elders, outdoor workers and persons living in higher floor levels, there was an increase usage of electrical fans or natural ventilation. Thermal comfort can be maintained by raised air movement and the perceived air quality could improve obviously by introducing outdoor air, which would create a good sleep environment to ensure sleep quality.

Place, publisher, year, edition, pages
Sage Publications, 2017
Keywords
Sleep quality, Sleep environment, Comfort, Questionnaire survey, Air conditioner, Electrical fan, Natural ventilation
National Category
Building Technologies
Identifiers
urn:nbn:se:umu:diva-108385 (URN)10.1177/1420326X15604206 (DOI)000394085700003 ()
Available from: 2015-09-10 Created: 2015-09-10 Last updated: 2018-06-07Bibliographically approved
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