A study on terraced apartments and their natural ventilation performance in hot and humid regions

Terraced apartments as a typology of the buildings are new approaches to meet energy conservation targets. This principle in the form of interactive spaces contributes to an incorporation of interior and exterior, daylight addition and exploitation of natural ventilation. This study mainly investigates the natural ventilation exploitation of a terraced apartment in the hot and humid region. One solid block and 4 porous apartments with different terrace depths (TD) are evaluated using computational fluid dynamics (CFD) analysis. The k-ε turbulence model was adapted to simulate airflow in and around a mid-rise building with 42 residential blocks. CFD analysis compares the effect of permeability in the form of terraces on wind behaviour and natural ventilation efficiency in a mid-rise building. Ventilation assessment parameters such as mean air velocity and mean age of air are measured to compare the natural ventilation performance. The simulation results clearly indicate that the implementation of permeability in the form of terraces can enhance building natural ventilation performance significantly. However, it is proved that some physical configurations such as terrace depth can influence this performance greatly. According to the results, increasing the terrace depth up to 1.2 meters will enhance the mean wind velocity 40%–88% inside the room, 10.61%–12.29% near the window and 63.44% on the openings. Velocity diagram follows a descending process after TD 1.2. The mean wind speed decreases to 25.53% inside the room, 15.09% inside terraces and 1.09% near the window. The average wind velocity on the openings is revealed to be 1.54 to 1.64 times larger in the porous models than the solid one. On the other hand, porous cases indicate lower values for the mean age of air compared to the solid model. This study provides proper guidelines to predict ventilation performance and to improve the design of naturally ventilated mid-rise buildings in hot and humid regions.     

Contribution of City Prosperity to Decisions on Healthy Building Design:A cases tudy of Tehran

In this paper,the city prosperity manifest is analyzed through a logical process and a framework is then proposed for designing healthy buildings in Tehran. The current status of urbanization in terms of the number of people living together and the changes in old behavior and perspectives have resulted in deficiencies to the health and hygiene of buildings apart from their surrounding environment. Consequently,these problems have affected people's well-being.This study mainly aims to determine policies and strategies for the architecturaldesign of healthy buildings according to health and safety conditions that influence the quality of internal spaces and external environment of cities.The study is conducted based on logical reasoning and uses focus group and in-depth interviews to assess the final result. The result is aframework that suggests a number of policies that can promote the mental and physical health as well as hygiene of residents through healthy buildings.     

Neuro-fuzzy predictive model for surface roughness and cutting force of machined Al–20 Mg2Si–2Cu metal matrix composite using additives

Neural Computing and Applications - Today’s metal matrix composites are widely used due to their excellent properties, which are useful for high-performance applications in the automotive and...     

Girih for Domes: Analysis of Three Iranian Domes

Drawing Girih is a challenging mathematical and geometrical principle for artists and artisans in the present and past. This paper is to determine how Girih have been embedded on curved surfaces such as dome, according to their curvature. For achieving this goal, the Dast-Gardan pattern is represented as a prominent and complex type. This pattern enables the designer to use diverse types of star polygons in one pattern depending on the curvature of the surface. The research hypothesis is examined by analyzing the patterns of three historic domes in Iran. The result shows that there is a relationship between the number of points of star polygons and the change of the dome curvature.     

Effects of industrial by-product based geopolymers on the strength development of a soft soil

Portland cement is traditionally used as a binder in ground improvement projects on soft soil foundations. The use of cement in ground improvement projects, however, is fraught with both, financial and environmental concerns due to its relatively high cost, the use of natural resources and the high carbon footprint from cement production. Attempts are being made to find alternative environmentally friendly binders with a low carbon footprint using industrial by-products such as fly ash (FA) and slag (S). Using waste by-products such as FA and S to produce geopolymer binders, as novel green cementitious materials, may provide an environmentally friendly and effective ground improvement option. In this study, the effect of adding geopolymers to a soft soil was investigated for usage in deep soil mixing (DSM) applications. The soil was a soft marine clay known as Coode Island Silt (CIS). Different combinations of FA and S with six combinations of sodium and potassium based liquid alkaline activators (L) were added to the soil to study the effects on its engineering and chemical properties. These changes were evaluated via an unconfined compression strength (UCS) test, scanning electron microscopy (SEM) imaging and energy-dispersive X-ray spectroscopy (EDS) tests. The tests were conducted after 3, 7, 14 and 28?days of curing. Based on the results, the important role of L in strength development was studied, and the combination of 30% NaOH with 70% Na₂SiO₃ was found to achieve the highest strengths. Furthermore, increasing the S content was found to result in significant improvements in strength. The excellent correlation between strength and stiffness shown in the results are expected to help in the development of relationships for strength prediction of these green binders in geotechnical applications. This study shows that FA and S based geopolymers can be used as sustainable binders in DSM projects, with significant environmental benefits.     

Adaptive-Network-Based Fuzzy Inference System Analysis to Predict the Temperature and Flow Fields in a Lid-Driven Cavity

Heat transfer behavior in a 2-D square lid-driven cavity has been studied for various pertinent Reynolds and Rayleigh numbers. The lattice Boltzmann method, a numerical tool based on the particle distribution function is applied to simulate a thermal fluid flow problem. Bhatnagar-Gross-Krook (BGK) is combined with the double population thermal Lattice Boltzmann model to solve mixed convection in a square cavity. An adaptive-network-based fuzzy inference system (ANFIS) method is trained and validated using BGK Lattice Boltzmann model results. The results show that the trained ANFIS model successfully predicts the temperature and flow fields in a few seconds with acceptable accuracy.     

Prevalence of Nitrite and Nitrate Contents and Its Effect on Edible Bird Nest's Color

Edible bird nests (EBNs) are important ethnomedicinal commodity in the Chinese community. Recently, But and others showed that the white EBNs could turn red by vapors from sodium nitrite (NaNO₂) in acidic condition or from bird soil, but this color‐changing agent remained elusive. The aim of this study was to determine the prevalence of nitrite and nitrate contents and its affects on EBN's color. EBNs were collected from swiftlet houses or caves in Southeast Asia. White EBNs were exposed to vapor from NaNO₂ in 2% HCl, or bird soil. The levels of nitrite (NO₂^?) and nitrate (NO₃^?) in EBNs were determined through ion chromatography analysis. Vapors from NaNO₂ in 2% HCl or bird soil stained white bird nests to brown/red colors, which correlated with increase nitrite and nitrate levels. Moreover, naturally formed cave‐EBNs (darker in color) also contained higher nitrite and nitrate levels compared to white house‐EBNs, suggesting a relationship between nitrite and nitrate with EBN's color. Of note, we detected no presence of hemoglobin in red “blood” nest. Using infrared spectra analysis, we demonstrated that red/brown cave‐EBNs contained higher intensities of C‐N and N‐O bonds compared to white house‐EBNs. Together, our study suggested that the color of EBNs was associated with the prevalence of the nitrite and nitrate contents.     

Rotational capacity of castellated steel beams

This paper numerically studies the behavior of castellated beams with two simply supported ends under moment gradient loading and investigates the effect of beam and braced lengths on rotational capacity of castellated beams. To assure the ability of numerical models in predicting the complex behavior (especially at the location of opening) as well as the failure modes, numerical models of two experimentally tested specimens are developed. Comparison of force–displacement curves and failure modes shows that neglecting the boundary condition of the specimens, the numerical method can properly predict the behavior of castellated beams. All geometrical properties of the beams are the same as the study parameters so that the finite element model of the corresponding plain‐webbed beams can be easily created by filling the web openings in castellated beams. The accuracy of finite element models of plain‐webbed beams is evaluated by comparing the moment–rotation behavior with that of numerical models developed by other researchers. Rotational capacity of castellated beams derived from numerical models is compared with that of the corresponding I‐shaped plain‐webbed steel beams, and it is observed that in the case of short beams, web openings reduce energy absorption and plastic moment capacity of the beams compared with that of long ones. Copyright © 2012 John Wiley & Sons, Ltd.     

Organic Semiconductor Nanotubes for Electrochemical Devices

Electrochemical devices that transform electrical energy to mechanical energy through an electrochemical process have numerous applications ranging from robotics and micropumps to microlenses and bioelectronics. To date, achievement of large deformation strains and fast responses remains challenging for electrochemical actuators wherein drag forces restrict the device motion and electrode materials/structures limit the ion transportation. Results for electrochemical actuators, electrochemical mass transfers, and electrochemical dynamics made from organic semiconductors (OSNTs) are reported. The OSNTs device exhibits high-performance with fast ion transport and accumulation in liquid and gel-polymer electrolytes. This device demonstrates an impressive performance, including low power consumption/strain, a large deformation, fast response, and excellent actuation stability. This outstanding performance stems from the enormous effective surface area of nanotubes that facilitates ion transport and accumulation resulting in high electroactivity and durability. Experimental studies of motion and mass transport are utilized along with the theoretical analysis for a variable–mass system to establish the dynamics of the device and to introduce a modified form of Euler-Bernoulli's equation for the OSNTs. Ultimately, a state-of-the-art miniaturized device composed of multiple microactuators for potential biomedical applications is demonstrated. This work provides new opportunities for next-generation actuators that can be utilized in artificial muscles and biomedical devices.     

Role of bazaars as a unifying factor in traditional cities of Iran: The Isfahan bazaar

A city is a vital organism that lives and grows like other organisms. Therefore, implementing development plans that would provide a sense of unity and integration in relation to the city as a whole is necessary. Traditional Iranian architecture is full of samples evolved during the course of Iranian history that can serve as architectural paragons of the city. In Iran's traditional cities, a sense of unity exists in various urban areas. The traditional city of Isfahan is one of the most valuable samples and was selected as the case study in this research. Accordingly, the most important questions of this research are as follows: (1) What is the role of bazaars in creating a sense of unity in the traditional cities of Iran? (2) How do bazaars play out their role in the integration of these cities? This research focuses on the concept of a “traditional city” to determine the role of bazaars in such cities. The results show that bazaars are crucial in giving a sense of integrity to the concept of a traditional Iranian city. Bazaars provide cohesion among the different parts of cities, such as residential areas, as well as socio-political and trade centers. This condition means that traditional bazaars play two important roles in traditional cities: (1) they interconnect the different parts of the city's physical structure; and (2) the crucial role of bazaars in a city's social and cultural structure brings about unity among the citizens in the city. Bazaars as a unifying element connect the main urban functions and guarantee the city's economic and social life.