Wall Ratio Research Articles

Relative instability ratios of bone wall defects in trochanteric hip fractures: A finite element analysis.

Background: For decades, medial and lateral wall fragments of trochanteric hip fractures were considered two pivotal factors that could influence the stability of postoperative femur-implant complex. However, most studies seemed to misunderstand the concept of the posteromedial fragment and equated it with the medial wall, which overlooked vital roles of the anteromedial wall. Roles of the posterior coronal bone fragment were also highlighted in some research. However, influences of the bone walls above the trochanteric fracture instability are yet to be investigated and quantified by means of finite element analysis. Methods: Eight trochanteric fracture fixation models with different wall defects were constructed. Outcome indicators were the von Mises stress of the implant models, the maximum/minimum principal strain, the risky tensile/compressive volume and the volume ratios of the bone models, the femoral head vertex displacement, and the fracture surface gap. Based on these indicator values, the relative instability ratios were computed. Results: Outcome indicators, absolute values, and nephograms of all models showed the same upward and concentrating trends with exerted hip contact loads shifting from static walking to dynamic climbing. Similarly, these indicators also exhibited the same trends when the eight models were solved in sequence. Moreover, the relative instability ratio of the medial wall (100%), particularly the anteromedial part (78.7%), was higher than the figure for the lateral wall (36.6%). Conclusion: The anteromedial wall played relatively pivotal stabilizing roles in trochanteric hip fractures compared with the posteromedial wall and the lateral wall, which indicated that orthopedic surgeons should attach more importance to the anteromedial cortex support in an operating theatre.

Investigation of optimal design damping force based on novel mechanical model for precast wall structures connected by vertical damping devices

Currently, a method for designing the damping force for precast wall structures with vertical damping devices has garnered increasing attention. Therefore, we propose a novel mechanical model for precast walls connected by vertical damping devices based on the continuous link approach and energy principle to compute the optimal design damping force. The proposed model is validated based on experimental data and numerical simulation results obtained using the ABAQUS finite element analysis software. Subsequently, the effect of the aspect ratio of the precast walls on the damping force is analyzed based on the numerical models established. Based on the analysis results, the correlation coefficient between the design and ultimate loads is determined, and a simplified method for computing the optimal design damping force is presented. Finally, the effectiveness of the proposed mechanical model in computing the optimal design damping force is demonstrated via the dynamic time-history analysis of precast wall structures. The efficacy of the proposed mechanical model overcomes the deficiency of the method for designing vertical damping devices, thus providing a foundation for further investigations into structural damage control.

Analysis of Solar Chimney Application for Building Heating and Cooling in Different Climates in China

Solar chimneys have been applied widely to various buildings under different climate conditions because of their superiority in improving the indoor environment and saving energy. A series of comparative studies of the performance of solar chimneys used in 12 cities in China under different climatic conditions was carried out. A typical solar chimney in a representative building was studied using numerical simulation and analyzed using orthogonal experiment methods. Results show that the optimal structural configuration and the significance of influencing factors of the solar chimney have strong seasonal consistency. The window-to-wall ratio and wall-to-south wall ratio are the most significant influencing factors. Among the 12 cities, the highest average indoor temperature of the case room could be decreased by 5.7°C in summer and increased by 6.7°C in winter. The cooling and heating loads could be reduced by 30%–100% and 46%–56% respectively. The research results can provide practical guidance for future passive solar technology design.

Prediction of combustion instabilities based on the Green's function in a three-dimensional annular combustor with multiple flames

The prediction of combustion instabilities is essential for modern annular combustors fed by multiple flames. This paper develops a model based on Green's function to study the interaction of multiple flame responses with different types in a three-dimensional (3D) geometry. The flame responses are described by flame transfer functions and are recognized as monopole sources in 3D cavities. Then the dispersion relation equation in the form of matrix is performed with the condition of equality of pressure. Thermoacoustic complex frequencies, mode structure, as well as the stability behaviors in combustor can be obtained in this model and the analysis is accomplished using Rayleigh index. The results are compared to the values of existing theoretical models and a good agreement is achieved. Furthermore, the effects of non-identical flame responses on complicated slanted mode under the condition of asymmetric are studied. In addition, the combustion instabilities of radial mode can be predicted by this model when the radial position distributions of the heat sources move in the case of small ratio of inner wall to outer wall.

Quantifying airway remodelling for research or clinical purposes: How should we normalize for airway size?

Quantifying airway remodelling for research or clinical purposes: How should we normalize for airway size?

Investigation of the Influence of Design Parameters on the Strength of Steel–Concrete Composite Shear Walls by Finite Element Simulations

In this paper, the influence of design parameters on the strength of steel–concrete composite shear walls is investigated by means of finite element (FE) simulations. The shear wall typology studied in this paper consists of multiple composite plate shear wall-concrete encased on one or both sides of the plates. The FE models include contact technology to capture debonding between concrete and steel, tensile cracking in concrete, and large deflection theory involving local instabilities. Some design parameters considered in this work are the height-to-width ratio of the steel plates and their thickness, number of steel plates, the cross-section of the columns, and the height-to-width ratio of the shear wall. Furthermore, a sensitivity analysis of the normalised shear strength per unit cost of structure for these design parameters is also studied. Our numerical predictions are validated successfully with experimental data reported in the literature, revealing the predictive capabilities of the model. The present results provide further insight into the structural behavior of steel–concrete composite shear walls and pave the way for the future development of more efficient and innovative steel–concrete composite systems.

Optimisation of commercial buildings envelope to reduce energy consumption and improve indoor environmental quality (IEQ) using NSGA-II algorithm

In this study, a commercial building envelope is optimised to reduce energy consumption while simultaneously increasing thermal and visual comfort. Design parameters include diameter ratio (ratio of the building large diameter to its small diameter), window to wall ratio (WWR), and orientation. The study is performed for two usages, including retail stores and supermarkets, and three different areas. According to the results, the building performance highly depends on its form. Increasing WWR generally reduces the thermal and visual comforts while increasing energy consumption. To reduce energy consumption and maintain indoor environment quality, the orientation angle of less than 30° is preferable. Also, the effect of building area on the cooling energy consumption is more considerable than the other objectives. Besides, the building usage impacts heating energy consumption noticeably more than other parameters. Finally, the best design parameters are suggested for different usages and areas based on the results.

Asymptotic Theory of Flapping Wing Propulsion in Extreme Ground Effect

This study, dedicated to flapping wing propulsion in immediate proximity to a wall or between closely spaced flat walls, makes use of the method of matched asymptotic expansions. Its purpose is to create a simplified parametric model of such a propulsion system based on a single major assumption: immediate closeness of oscillating wing to a solid wall. In the case of a rectangular finite-aspect ratio wing, analytical expressions have been obtained for the coefficients of instantaneous and period-averaged thrust force as well as for the efficiency of the propulsor as a function of distance from the wall, Strouhal number and wing aspect ratio for selected cases of heaving, pitching and combined oscillations. It is shown that for some oscillation modes closeness to the ground results in increases in thrust and efficiency, and that optimally combined (considering ratio of the amplitudes and phase shift of contributing motions) heave–pitch oscillations allow to maximize thrust or efficiency of the flapping-wing propulsor. Increase in aspect ratio and decrease in Strouhal number (relative frequency of oscillations) in the case of heaving invariably brings about the increase in the ideal efficiency. An example is provided of a non-planar extreme ground effect application considering oscillations of a ring-wing embracing circular cylinder. A rule is derived for recalculation of the characteristics of the flapping-wing propulsor near a flat wall onto the characteristics of the same wing operating in a narrow canal between parallel walls. This rule can also be applied to evaluate propulsive properties of a ring-wing oscillating between co-axial cylindric surfaces.

A SIMPLE EVALUATION OF THE WALL AND COLUMN WALL RATIOS OF LOW-RISE RC BUILDINGS BASED ON ENERGY BALANCE FOR CONTINUED USE AFTER EARTHQUAKES

This paper examines the wall and column wall ratios of low-rise RC buildings to determine wall and column wall ratios that would limit the degree of building damage to a level no greater than slight damage for the purpose of continued use of the building after a mainshock, foreshock, or aftershock. Based on the energy balance in seismic response, a simple evaluation formula was derived to calculate wall ratio to a strength that would allow walls to withstand a level of damage up to shear cracking after an earthquake. The applicability of this formula was confirmed by comparing the wall ratio of actual buildings based on earthquake damage surveys with the results of this evaluation formula. The results indicated standards for wall and column wall ratios that enable buildings to withstand being hit by one to three earthquakes of an extremely rare level, as described in the notice, and still sustain a level of damage below shear cracking.

Study on Seismic Performance of Cold-Formed Thin-Walled Steel-Straw Board Composite Wall with Diagonal Brace

The composite wall studied in this paper is based on the original cold-fonned thin-walled steel-straw board composite wall, which is set up with inclined braces and rigid inclined braces to improve its seismic performance. The factors of aspect ratio are analyzed, and the formula of shear bearing capacity of composite wall is deduced. The results show that: (1) When the height-width ratio of the composite wall is 2.4m×1.2m, 1.8m×1.2m and 1.2m×1.2m respectively, the yield strength of the composite wall is 35.78kN, 37.47kN and 54.23kN respectively. The yield strength of the former increases by 4.72 %, and the yield str ength of the latter increases by 44.73 %. (2) Using the effective strip method, the error of the derived shear capacity formula is not large, and the difference between the experimental value and the simulated value is not large, in order to provide some reference for the seismic design of this kind of cold-fonned thin-walled steel-strawboard composite wall with diagonal brace.

Optimization analysis of residential space in cold region based on building performance simulation

Purpose-Rural residential buildings in China?s cold areas still have large room for improvement in lighting, energy saving and other aspects due to their own development lag. Design/methodology/approach-Taking Zhaoyuan County residential buildings as an example, the spatial elements of residential buildings are quantified, and the variation intervals of each spatial element are determined based on this. Then the standard model of residential buildings is constructed, and the changing trend and related mechanism of heating energy consumption and natural lighting under the change of residential space elements are discussed. Findings-The results show that: in terms of heating energy saving, there is an obvious optimal solution between the window wall ratio of the south facade and the orientation of residential buildings; in indoor natural lighting, all spatial elements show positive and negative correlation without considering glare; building depth, eave height and plane girth area ratio are the key variables affecting heating energy consumption. Window to floor ratio, building eave height, building depth, and plane aspect ratio are the key variables that affect indoor lighting. The research results can provide reference for the energy-saving construction of residential buildings in cold areas.

The HVAC model predictive control of building thermal dynamic characteristics

As the terminal energy user of urban power grid, it is significant to model and simulate the energy consumption characteristics of buildings. First, the author proposes a thermal dynamic model to predict the energy consumption of building refrigeration/heating, it is composed of several groups of heat transient energy balance equations, which can fully consider the impact of heat convection, heat conduction and heat storage on building energy consumption during the heat transfer process of building envelope. Then, the HVAC model predictive control (MPC) method considering the thermal dynamic characteristics of the building envelope is proposed for the heating, ventilation and air conditioning, the core energy unit of the building, the change of window wall ratio in building will affect the thermal insulation performance of the building, so the window wall ratio in building design should not exceed 0.7. From the perspective of building thermal insulation performance, the author analyzes the situation that the total 48 hours operating cost of buildings under two control methods changes due to the change of building thermal insulation performance with the change of window wall ratio in different environments, the simulation results show that when using MPC control method for HVAC, the daily operating cost of buildings increases with the window wall ratio at a lower rate than the traditional control method. It can be seen that the MPC control method has a better effect of energy saving and reducing the total operating cost of buildings in response to the environment where the window wall ratio of buildings increases or the thermal insulation performance of buildings becomes worse over time. It is proved that the HVAC control method based on MPC not only helps to reduce the building energy cost, but also deals with the reduction of HVAC energy efficiency level and the deterioration of building insulation performance, it is more conducive to saving energy and improving the operating economy of buildings.

Optimization of an office building form using a lattice incubate boxes method

With the increasing demand for sustainable built environments, energy performance is becoming essential in the early design stage. Several previous studies using optimization of building form for energy performance considered simple hypothetical forms. In addition, previous multi-objective optimization (MOO) of building form and envelope did not consider views percentage to the outdoor (VPO) despiteof its importance for human mental health and its conflict with energy performance. This paper proposes a novel lattice incubates boxes (LIB) method that optimizes a cellular office building form. It considers the entire building with 27 thermal zones in an attempt to mimic a real case study. In addition, it considers VPO as an objective in the MOO of building form and envelope. First, the study performs single-objective optimization (SOO) of architectural form and orientation for annual thermal Energy Use Intensity (EUI) in Cairo, London, and Chicago. Second, it performs multidisciplinary MOO of Cairo’s form, window to wall ratio (WWR) and horizontal shading devices (HSD) for annual thermal EUI, annual Useful Daylight Illuminance (UDI-100–2000), and VPO. Third, it develops the LIB method to make it more applicable in professional practice through considering 72 individual thermal zones while adding more constraints. Compared to the initial forms, first part EUI savings were between 16.86% and 12.9 %. EUI, UDI, and VPO savings for Cairo in the second part were 20.16%, 11.5%, and 19.5 %. Scatterplots are developed for the second part that show rows motion has the highest positive impact on UDI and VPO, WWR has a positive impact on all objectives and HSD has high positive impact on EUI only. Savings in the third part are 11 % EUI, 8.77 % UDI, 2.86% Daylight Autonomy (DLA) and 7.8 % VPO. Scatterplots in the third part show that almost all proposed form dynamic parameters have strong impact on all objectives.

Investigating the Effect of Different Proportions of Iwan and Window Area of Adjacent Room on Cooling/Heating Load and Energy Consumption in Central Courtyard Model in Yazd

The city of Yazd has a large number of traditional houses. Houses with central courtyards and an Iwan were suitable for establishing thermal comfort conditions. In this research, the effect of Iwan's depth and the ratio of the adjacent room's openings on the comfort condition in the residential courtyard buildings in Yazd city were evaluated. The current research aims to provide an optimal model of the Iwan to increase sustainable development and use such models as the Iwan in contemporary housing in the hot and dry climate of Yazd. In order to investigate the effect of parameters, samples from the north-facing room and south-facing room in a central courtyard model with different proportions of the Iwan and different sizes of the window were simulated in Design Builder software. The results showed that the depth of Iwan and window to wall ratio's (WWR) of the adjacent room’s window significantly affects the comfort (according to cooling load, heating load, and energy consumption) in this room. The results obtained in this research will be a new window to recover the concepts of old patterns and help to solve climate problems.

Analyzing the effects of passive design strategies on building ventilation performance and thermal comfort using simulation-based approach

One of the sustainable approaches to improving indoor thermal comfort and building ventilation efficiency, particularly in developing and populated countries, is to implement the optimum passive design solutions. However, the interaction between ventilation performance, indoor thermal comfort, and passive design features of buildings is scarcely studied in the domain of airflow modeling. Therefore, this study aims at assessing the ventilation performance and indoor thermal comfort with regards to passive design strategies, specifically, opening characteristics such as the Opening to Wall ratio (OWR) and Window to Wall ratio (WWR) in a Computational Fluid Dynamics (CFD) environment. The CFD simulations run is found pivotal for determining the spatial variation of Predicted Mean Vote (PMV) and Predicted Percentage Dissatisfied (PPD) to gauge thermal comfort and the natural ventilation performance in terms of air change rate per hour (ACH). The proposed methodology is implemented in classroom spaces of an academic building located in a warm and humid region. In the study, a field investigation is carried out to collect precise temperature and air velocity data needed to validate the resulting CFD model. The findings show that increasing OWR and WWR percentages can enhance ventilation efficiency and indoor thermal comfort.

Storage stability of microencapsulated anthocyanin extracted from kokum (Garcinia indica) rind

The present research aimed to study the storage stability of microencapsulated anthocyanin. The anthocyanin was extracted from kokum processing industry waste and microencapsulated by spray drying. The effect of different process variables like core (i.e., anthocyanin) to wall (i.e., maltodextrin) ratio, inlet temperature and feed rate on encapsulation efficacy (EE) and Encapsulation yield (EY) was observed. The storage stability of anthocyanin was carried out by subjecting it to different storage conditions like the presence and absence of air, sunlight, room temperature, and refrigeration condition. The maximum EE (82.2±0.95%), and EY (92.6±0.86%) were recorded at the core to wall ratio (1:3), inlet temperature (140°C), and feed rate (2 mL/mins). The highest retention was recorded in encapsulated anthocyanin stored in refrigerated conditions (R2 = 0.982), with a half-life of 245.77 weeks, and a D value of 354.57 weeks. This concludes that the stability of anthocyanin was increased due to encapsulation

Optimization of Indoor Thermal Performance Through Orientation and Vertical Greenery Percentage Analysis in High-Rise Residential, Malaysia

Vertical Greenery System (VGS) is one of the passive solutions for urban greening that emphasizes application of building envelope. It can improve both indoor thermal performance and energy efficiency in the longer run. To realize this effort, proper orientations are identified as the main key factors. As high-rise buildings are being develop throughout urban cities in Malaysia, indoor spaces received high amount of solar radiation due to improper orientation and site constraint exposure that mainly comes from East and West. To overcome this issues, orientation study and vertical percentage analysis were conducted in this paper. Investigation on the importance of having proper façade orientation and greenery percentage in urban cities are the main purpose of this research. Several methods that involved empirical studies and simulation using IESVE software were conducted to fulfil this investigation. Based on the findings, the highest reduction in both temperature and cooling load energy using vertical greenery system can be tabulated in the following order: East > West > South > North. It is suggested, that both the East and West orientations to be the best façades to implement the VGS. Both facades received direct sunlight in the morning and evening sessions, enabling the VGS envelope to reduce the indoor dry bulb temperature and building cooling load energy more efficiently at higher altitude. For vertical greenery percentage analysis, higher percentage of vegetation will result in a more positive effect towards the reduction of indoor dry bulb temperature. In conclusion, the incorporation of a 100% VGS window wall ratio coverage is shown to have a reduction of 1.42°C and it was estimated at least 16.9% for building cooling load energy saving.

A Pilot Study on the Effect of Daylighting and Orientation in the Office Building: A Case of Kathmandu

Illuminance results in visibility of objects and daylighting is the major source of light for perceiving and carrying out certain function. Office blocks hold the space for people to perform economic task for 7-8 hours daily and humans seek comfort. Lighting the interior is a mindful job, as the space can be over lit or under lit resulting in visual discomfort and high use of energy to maintain human comfort. Quality and quantity of natural light in the indoor is guided by several factors such as climate, latitude, sky condition, site obstructions, orientation, opening design, surface reflectivity, space function etc. The study shows that the best orientation for Kathmandu is 175°N and for the building with window wall ratio greater than 60%, orientation does not play a vital role. Autodesk Ecotect 2011, has been used to simulate the building with the real case scenario in the urban context for the outmost result. The finding adds value during the early design phase and also to prepare guidelines, policies and bylaws relating to wellbeing of occupant for visually and functionally friendly interior.

Determination of Minimum Shear Wall Ratio for the Compatibility Behavior of Shear Wall-Frame in Earthquake Resistant Design of Reinforced Concrete Structural Systems

Depreme dayanıklı yapı tasarımında kat adedi arttıkça, taşıma kapasitesini aşmamak, yatay ötelenmeleri sınırlamak ve çerçeve içi bölme duvarların hasar görmesini engellemek için betonarme perde elemanların kullanımı zorunlu hale gelmektedir. Depreme maruz kalmış yapılar incelendiğinde, bazı binalarda yeteri kadar betonarme perde eleman bulunmamasından dolayı, yatay ötelenmelerin sınır değerleri aştığı, perde elemanların daha büyük kesme gerilmelerine maruz kaldığı ve beklenmedik öncül gevrek kesme göçmelerinin perdelerde ortaya çıktığı görülmektedir. Betonarme çerçeve sisteme kısmi perde elemanların eklenmesiyle çerçeve sistem davranışının karma sistem davranışına evirildiği, perde oranının daha da arttırılmasıyla, konsol kirişe benzetilen perde duvar davranışına geçtiği bilinmektedir. Yatay deplasmanları sınırlamak için sadece tek bir kat alanına bağlı olarak gerekli perde duvar alanının belirlenmesi üzerine birçok çalışma bulunmaktadır. Burada ise binanın perde duvar davranışı göstermesi için kolon ve perdelerin ön tasarımı aşamasında, donatı artış oranına bağlı olarak bina maliyetindeki artış ve perde-çerçeve davranış uyumluluğu dikkate alınarak, perdelerin karşıladığı momentin bina taban momentine oranına bağlı, bir kattaki perde alanının tüm katların alanına oranının minimum değeri tespit edilmeye çalışılmıştır. Bu amaçla, Türkiye Bina Deprem Yönetmelik (TBDY-2018) kurallarına uygun çerçeve sistemden oluşan beş katlı ve planda simetrik bir bina tasarlanmıştır. Öncelikle, kiriş-kolon çerçeve sistemden oluşan bu modele asansör perdesi eklenmiş, daha sonra asansörlü modele çeşitli oranlarda simetrik perdeler ilave edilerek toplamda 10 model oluşturulmuştur.

Preparation and Performance of Microencapsulated Sealing Material for Coal Mine Gas Drainage.

The performance of coal mine gas extraction borehole sealing material plays an essential role in the efficiency of gas extraction. Microcapsule technology was proposed to delay the expansion time of sealing materials to address the ineffective expansion of cement-based sealing materials in hydration. Based on conventional cement-based sealing materials, delayed-expansion microcapsules were prepared by phase separation with ethyl cellulose (EC) as the capsule wall material and montmorillonite (MMT) as the core material. A single-factor experiment showed that the delayed-expansion microcapsule had the best comprehensive effect when the EC content was 3%, the stirring rate was 400 rpm, the MMT content was 3.5%, and the core-wall ratio (CWR) was 10:3. Second, the slow release effect of the cement samples under the action of microcapsules is remarkable through physical tests. In addition, the triaxial compression test results show better mechanical properties of the delayed-expansion sealing materials. Then, nuclear magnetic resonance scanning was applied to the coal samples injected with different sealing materials. It was found that the proportions of macropores and mesopores in the total pore volume in the coal sample at 50 and 100 mm from the borehole wall decreased by 12.28 and 11.82%, respectively, indicating that the delayed-expansion sealing material has a better sealing effect.