Development of a Controlled-Ventilation Box for Modified-Atmosphere Storage of Fresh Produce

Adjusting beneficial gas concentrations in real time in response to changing storage conditions is important for fresh produce, especially throughout the supply chain when temperature abuse occurs frequently. In this study, a controlled-ventilated box for bulk transportation of fresh produce was demonstrated and tested under variable temperatures. The presented system comprised a rigid container with a miniature blower installed in the opening of its wall for facilitating the gas exchange and an additional wall opening with a metal tube protruding into the inner container’s space. The in-package atmosphere was formed by the balance between the respiratory activity of the produce and the influx of fresh air through the wall openings, regulated by switching the blower ON or OFF. The mass transfer coefficient for metal tubes of different dimensions was measured under modified atmosphere featuring 15% CO2 and 5% O2 at 10 °C. The addition of an air blower increased the mass transfer coefficient by at least 100 times. A further storage trial with cherries was successfully performed at 10 °C and 20 °C. The demonstrated trial featured some significant inputs to increase the knowledge about better storage of fresh produce throughout the supply chain and storage.

Experimental Study on Fire Risk Assessment of Windows by Material (II)

In this study, the fire safety standards for windows in Korea, the United States, and Japan were compared to prevent fire expansion through exterior wall openings. Experiments on polyvinyl chloride (PVC) and aluminum window frames widely used in Korea were performed. The tests were conducted according to KS F 2845, in which frames with equal thickness and area in a single-window form and 1 h fire-resistance glass with an 8 T thickness were combined. The experimental results showed that the PVC window was approximately 9 min, and the aluminum window was approximately 26 min. However, in Korea, there are no test standards for windows installed at the opening of exterior walls. In addition, fire safety standards for windows should be established along with designations of fire prevention zones.

Improving natural ventilation in renovated free-stall barns for dairy cows: Optimized building solutions by using a validated computational fluid dynamics model

Natural ventilation is the most used system to create suitable conditions, removing gases, introducing oxygen in livestock buildings. Its efficiency depends on several factors and above all on the number, the dimensions and the position of wall openings and internal layout of livestock buildings. The aim of this research was to develop optimized layout solutions for improving natural ventilation effectiveness in free-stall barns for dairy cows by using a CFD approach. A validated computational fluid dynamics (CFD) model was applied in a case study which is highly representative of building interventions for renovating the layout of free-stall barns for dairy cows located in an area of the Mediterranean basin. Firstly, dairy cow behaviour was analysed by visual examination of time-lapse video-recordings. Then, simulations were carried out by using the validated CFD model and changing the position of internal and external building elements (i.e., internal office and external buildings for milking) in order to find the best condition for the thermal comfort of the animals. The results showed that the best conditions were recorded for a new configuration of the building in terms of air velocity distribution within the resting area, the service alley and the feeding alley for dairy cows, and in the pens for calves. In this new layout, the office areas and the north-west wall openings were located by mirroring them along the transversal axis of the barn. Therefore, the CFD approach proposed in this study could be used during the design phase, as a decision support system aimed at improving the natural ventilation within the barn.

Evaluation of building security costs determinant within the built environment in Minna, Niger state, Nigeria

Building equipped with protective measures is exceedingly restricted but it brings about a moderately high increment in expenses of building security and the general cost of the home. This study aims at assessing the built environment experts’ perception of factors affecting the cost of maintaining security in houses as a part of sustainable building security cost. The study employed mixed methods sequential exploratory design to source data primarily from the respondents. Purposive and convenience sampling were used for data collection while descriptive statistics and inferential were employed for data analyses. The results revealed insignificant difference in respondents’ perceptions on building security costs. The top ranked respondents’ perceptions were from Builders, Quantity Surveyors and Architects with total mean scores of 267.08, 234.66 and 234.63. No significant variations were shown among the mean scores of the items ranked. This is an indication that all items are important therefore having effect on building security costs. The study concluded that external wall openings access prevention, size of building, perimeter fence and protection are some of the key criteria for measuring building security costs. The study sensitizes the built environment experts, criminologists and policy makers about the implication of the established factors on building security costs. Keyword: Built-Environment, Building security, Cost determinant, Experts’ perceptions

Structural Identification of Masonry Residential Buildings Considering Wall Openings

Although one-story residential masonry structures are thought not to be vulnerable to seismic actions, many heavily damaged and/or collapsed instances of these types of structures have been observed in the past strong earthquake events. Hence, the evaluation of their safety requires much attention in terms of more precise numerical models. In-situ vibration tests together with laboratory tests on masonry specimens provide valuable information for structural parameter identification that can be used to develop accurate numerical models. These numerical models then can be used for evaluation of the response and seismic safety. While many specific methods and parameters can be adopted in numerical modeling, linear material properties of a structure are expedient in response analysis. Hence, an equation to be used to determine the homogenized linear model parameters for masonry walls with openings is proposed in this study. The equation has been developed based on the percentage of the openings on the wall. The effect of wall openings on the stiffness and the total strength of one-story masonry structures have been evaluated by using the experimental data and the calibrated finite element models. In-situ ambient vibration and material tests have been conducted on three masonry buildings with identical materials and the results from these experiments were used to verify the accuracy of the formulation.

A Flexible Inference Machine for Global Alignment of Wall Openings

Openings such as windows and doors are essential components of architectural wall surfaces. It is still a challenge to reconstruct them robustly from unstructured 3D point clouds because of occlusions, noises and non-uniformly distributed points. Current research primarily focuses on meliorating the robustness of detection and pays little attention to the geometric correctness. To improve the reconstruction quality, assumptions on the opening layout are usually applied as rules to support the reconstruction algorithm. The commonly used assumptions, such as the strict grid and symmetry pattern, however, are not suitable in many cases. In this paper, we propose a novel approach, named an inference machine, to identify and use flexible rules in wall opening modelling. Our method first detects and models openings through a data-driven method and then refines the opening boundaries by global and flexible rules. The key is to identify the global flexible rules from the detected openings, composed by various combinations of alignments. As our method is oblivious of the type of architectural layout, it can be applied to both interior wall surfaces and exterior building facades. We demonstrate the flexibility of our approach in both outdoor and indoor scenes with a variety of opening layouts. The qualitative and quantitative evaluation results indicate the potential of the approach to be a general method in opening detection and modelling. However, this data-driven method suffers from the existence of occlusions and non-planar wall surfaces.

Numerical analysis of the effect of external opening on fire safety of refuge floors in tall buildings

Refuge floors are fire safety requirements for tall buildings in many Asia-Oceania cities. However, there are concerns on the adequate provision of cross-ventilation and drencher system to openings on refuge floors. To review the existing situation, a survey of 44 building developments involving 51 blocks of both residential and non-residential tall buildings was conducted. A new fire safety parameter, i.e. the ratio of external wall openings areas to the nominal total wall areas of refuge floors (wall opening area ratio, or WOAR), was introduced to provide a quantitative measure in analysing fire safety level of tall buildings. To study how the ventilation provision is affected by WOAR, numerical simulations for the effect of natural ventilation on fire growth on the refuge floor were conducted by incorporating the wind data collected from the tallest building in Hong Kong. In the simulations, an office layout was adopted on both upper and lower floors for the sake of illustrating the possible smoke and heat spread from lower floor to upper floor (refuge floor). Finally, fire safety issues in relation to natural ventilation on fire in tall buildings were discussed. Suggestions in improving the fire safety design of tall buildings are proposed.