Two Constructal Routes to Minimal Heat Flow Resistance via Greater Internal Complexity

1999 ◽  
Vol 121 (1) ◽  
pp. 6-14 ◽  
Author(s):  
A. Bejan ◽  
N. Dan
Keyword(s):  
Heat Flow ◽  
Numerical Solutions ◽  
Design Method ◽  
Flow Path ◽  
High Conductivity ◽  
Constructal Theory ◽  
Size Growth ◽  
Growth Method ◽  
Overall Resistance ◽  
And Performance

This paper shows that the geometry of the heat flow path between a volume and one point can be optimized in two fundamentally different ways. In the “growth” method of the original constructal theory the structure is optimized starting from the smallest volume element of fixed size. Growth, or optimal numbers of constituents assembled into larger volumes, is one route to resistance minimization. In the “design” method the overall volume is fixed, and the designer works “inward” by optimizing the internal features of the heat flow path. The design method is new. It is shown analytically that the two methods produce comparable geometric results in which the high-conductivity channels form constructal tree networks, and where the low-conductivity material fills the interstices. For simplicity, it is assumed that the high-conductivity channels and their tributaries make 90-deg angles. In both approaches, the overall resistance decreases as the internal complexity of the conductive composite increases. In the growth method the number of constituents in each assembly can be optimized. In the design method, some of the constituent numbers cannot be optimized: these numbers assume the roles of weak parameters. The growth method is the simplest, and provides a useful approximation of the design and performance that can be achieved using the design method. Numerical solutions of the volume-to-point optimization problem confirm the results obtained analytically, and show that the geometric features of the optimal design are robust.

scholarly journals A modular design method based on TRIZ and AD and its application to cutter changing robot

2021 ◽  
Vol 13 (7) ◽  
pp. 168781402110343
Author(s):  
Mei Yang ◽  
Yimin Xia ◽  
Lianhui Jia ◽  
Dujuan Wang ◽  
Zhiyong Ji
Keyword(s):  
Modular Design ◽  
Design Method ◽  
Idea Generation ◽  
Design Parameters ◽  
Problem Analysis ◽  
Concept Design ◽  
Functional Requirements ◽  
Shield Tunneling ◽  
Structural Hierarchy ◽  
And Performance

Modular design, Axiomatic design (AD) and Theory of inventive problem solving (TRIZ) have been increasingly popularized in concept design of modern mechanical product. Each method has their own advantages and drawbacks. The benefit of modular design is reducing the product design period, and AD has the capability of problem analysis, while TRIZ’s expertise is innovative idea generation. According to the complementarity of these three approaches, an innovative and systematic methodology is proposed to design big complex mechanical system. Firstly, the module partition is executed based on scenario decomposition. Then, the behavior attributes of modules are listed to find the design contradiction, including motion form, spatial constraints, and performance requirements. TRIZ tools are employed to deal with the contradictions between behavior attributes. The decomposition and mapping of functional requirements and design parameters are carried out to construct the structural hierarchy of each module. Then, modules are integrated considering the connections between each other. Finally, the operation steps in application scenario are designed in temporal and spatial dimensions. Design of cutter changing robot for shield tunneling machine is taken as an example to validate the feasibility and effectiveness of the proposed method.

scholarly journals Talent and student private rented sector bottlenecks: a preliminary UK investigation

2015 ◽  
Vol 33 (3) ◽  
pp. 287-302 ◽  
Author(s):  
Simon Huston ◽  
Arvydas Jadevicius ◽  
Negin Minaei
Keyword(s):  
Preliminary Investigation ◽  
Secondary Data ◽  
Content Type ◽  
Service Levels ◽  
Macroeconomic Analysis ◽  
Management Procedures ◽  
Size Growth ◽  
And Performance ◽  
The Uk ◽  
Rented Sector

Purpose – The purpose of this paper is to sketch the UK housing backdrop, review the student private rented sector (PRS) and assess the experience of post-graduate university student tenants in the PRS. Design/methodology/approach – A literature review puts the issues of student-PRS responsiveness into context and helps to untangle some UK housing issues. The private sector’s size, growth and performance is assessed by reviewing secondary data. In-depth interviews were then conducted at a regional university campus. Findings – The study confirms accumulating evidence of an unbalanced UK housing market. The study identified four main PRS issues: first, rapid university expansion without accompanying residential construction has sparked rampant PRS growth with, second, quality issues, third, in tight letting market conditions, rented agent service levels fell and fourth, part of the problem is complex PRS management procedures. Research limitations/implications – The research has three noteworthy limitations. First, the macroeconomic analysis integrated secondary research without independent modelling. Second, the views of letting agents, university property managers, planning officers or landlords were not canvassed. Finally, the pilot interviews were geographically restricted. Practical implications – When they expand, universities, local authorities and industry players need to give due consideration to plan for, design and develop quality student accommodation. Over-reliance on the PRS without informed oversight and coordination could undermine student experience and erode long-term UK competitiveness. Social implications – The lack of quality student rented accommodation mirrors a general housing malaise around affordability, polarisation and sustainable “dwelling”. Standards and professionalism in the rented sector is part of the overall quality mix to attract global talent. Originality/value – The preliminary investigation uses mixed-methods to investigate PRS service delivery. It illustrates the interplay between professional property management and wider issues of metropolitan productivity, sustainability and resilience.

scholarly journals Effectiveness of using the iPad in Learning to Acquire the Mental and Performance Skills in Teaching Social Studies Curriculum

2017 ◽  
Vol 6 (1) ◽  
pp. 1
Author(s):  
Maadi Mahdi Alajmi ◽  
Hanan Abdullah Al-Hadiah
Keyword(s):  
Social Studies ◽  
Test Score ◽  
Design Method ◽  
Statistical Processing ◽  
Traditional Learning ◽  
Control Group ◽  
Mental Performance ◽  
Eighth Grade Students ◽  
Post Test ◽  
And Performance

This study aims to examine the effectiveness of using the iPad in learning to acquire the mental and performanceskills in teaching the social studies. Using experimental design method, the study compared two groups: (a)experimental, taught using the iPad, and (b) control group, taught using the traditional learning without iPad. A totalof 48 (24experimental group and 24 control group) eighth grade students in state of Kuwait participated in this study.The study started on the second semester on 2015-2016 on the average of 6 weeks. After the test on the study sampleand the statistical processing, the results revolved that: (1) there are no significant differences between theexperimental and the control group in mental performance in pre-test score. (2) There are no significant differencesbetween the experimental and the control group in skills performance in pre-test score. (3) There are significantdifferences between the experimental and the control group in mental performance in post-test score in favor ofexperimental group. (4) There are significant differences between the experimental and the control group in skillsperformance in post-test score in favor of experimental group. Based on the results, the study concluded withrelevant recommendations regarding the implementation of using iPad technology in education, and suggested somefurther studies in this topic.

scholarly journals Analysis of Post Loan Disbursement Allocation and Performance of Non-Prime Household Loan in Microfinance Banks in Kenya

2017 ◽  
Vol 03 ◽  
pp. 42
Author(s):  
Bernard Ndirangu Wachira ◽  
Humphrey Opiyo Omondi ◽  
Josphat K. Kinyanjui ◽  
◽  
◽  
...  
Keyword(s):  
Financial Management ◽  
Design Method ◽  
Wald Test ◽  
Grameen Bank ◽  
Credit Risks ◽  
Training Policy ◽  
The Government ◽  
And Performance ◽  
Descriptive Survey ◽  
The Relationship

The part played by non-prime household loans in improving the lives of many people who cannot afford collateral globally cannot be ignored. Many Microfinance Banks in many economies worldwide have tried to maintain the Grameen Bank Model of granting microloans, mainly non-prime household loans. However, the credit risks associated with this initiative hamper the pace at which the granting of this credit facility is expected to grow. This study intends to explore the relationship between the post loan disbursement allocation and the performance of non-prime household loans in the Microfinance Banks in Kenya. The theory associated to this study is the Credit Risk Theory. This theory, which is regarded as credit structural theory, was developed by Merton in 1972. The descriptive survey research design method was applied, and the sample size was 150 respondents. The data-collection tool used was a questionnaire. A logistic regression analysis was conducted for the purpose of predicting non-prime household performance in the Microfinance Banks using training budget, recoveries budget, percentage of training budget, and percentage of recoveries budget as predictors. The Wald test shows that training budget, recoveries budget, and percentage of training budget were good predictors, making a significant contribution to prediction. The percentage of budget on recoveries was not a significant predictor. The Microfinance Banks should enhance the performance of non-prime household loans through capacity building to the borrowers and educate the borrowers on dangers of enforced loan recoveries. The government, through the Central Bank of Kenya, should have a training policy for the Microfinance Banks so that they can enlighten the borrowers on proper financial management to avoid conflicts with borrowers during loan recoveries.

scholarly journals Desain Bilik Sterilisasi "White Box"

2021 ◽  
Vol 17 (1) ◽  
pp. 68-75
Author(s):  
Noor Hamidah ◽  
Dwi Anung Nindito ◽  
Tatau Wijaya Garib ◽  
Waluyo Nuswantoro ◽  
Mahdi Santoso
Keyword(s):  
Performance Test ◽  
Design Method ◽  
Skin Surface ◽  
The Body ◽  
Piping System ◽  
Design Activity ◽  
Test Function ◽  
Function Test ◽  
And Performance ◽  
Implementation Stage

ABSTRACT The sterilization chamber is designed to sterilize the body using a filler formulation that is not harmful to the skin surface. Formulation, namely the composition of filler fluids (type, dose and amount) using substances that are safe for the body accordingly, certainly provides benefits. The use of the sterilization booth uses the correct and safe filling fluid. The sterilization chamber uses a mist nozzle sprayer (with the appropriate discharge) to spray the filling liquid so that the user is safe. This sterilization booth is named "White Box". This "White Box" research aims to design (functional and structural) and test (function test and performance test) on a system and mechanism for condensing the condensation of a humidifier that can fill the sterilization room optimally. The design method of the "White Box" sterilization booth uses a qualitative method with the following phases: (1) The preparation stage, namely the functional design and the structural design of the "White Box"; (2) The implementation stage is analyzing the use of tools and materials and making sterilization booths; (3) Post-implementation stage, namely testing the sterilization chamber, including the function test and performance test of the sterilization chamber. The design activity of the "White Box" sterilization booth was carried out by testing various variations of the prototype, including variations in the dimensions of the distribution pipe, the shape of the distribution pipe, and variations of the piping system. The validation process includes: (1) The diameter of the pipe against humidifier dew bursts; (2) The shape of the piping against humidifier dew spray; and (3) the length of the pipe passage to the humidifier dew spray. ABSTRAKBilik sterilisasi didesain untuk mensterilisasi tubuh dengan menggunakan formulasi zat pengisi yang tidak berbahaya bagi permukaan kulit. Formulasi yaitu komposisi cairan pengisi (jenis, takaran dan jumlah) menggunakan zat yang aman bagi tubuh yang sesuai, tentu memberi manfaat. Penggunaan bilik sterilisasi menggunakan cairan pengisi yang benar dan aman. Bilik sterilisasi menggunakan mist nozzle sprayer (yang debitnya sesuai) untuk menyemprotkan cairan pengisinya sehingga pengguna aman. Bilik sterilisasi ini diberi nama "White Box". Penelitian "White Box"ini bertujuan merancang (fungsional dan struktural) dan menguji coba (uji fungsi dan uji kinerja) pada sebuah sistem dan mekanisme penyaluran pengembunan dari alat humidifier yang mampu memenuhi ruang bilik sterilisasi secara optimal. Metode rancang bangun bilik sterilisasi "White Box" menggunakan metode kualitatif dengan tahap kegiatan meliputi: (1) Tahap persiapan yaitu rancangan fungsional dan rancangan struktural"White Box"; (2) Tahap pelaksanaan yaitu analisa penggunaan alat dan bahan dan Pembuatan bilik sterilisasi; (3) Tahap Pasca Pelaksanaan yaitu pengujian bilik sterilisasi antara lain uji fungsi dan uji kinerja bilik sterilisasi. Muatan kegiatan rancang bangun bilik sterilisasi "White Box" dilakukan dengan cara menguji coba berbagai variasi prototipe, meliputi variasi dimensi pipa penyaluran, bentuk pipa penyalur, variasi sistem perpipaan. Proses validasi yang dilakukan meliputi: (1) Diamater pipa terhadap semburan embun humidifier; (2) Bentuk pipa penyalur terhadap semburan embun humidifier; dan (3) Panjang lintasan pipa terhadap semburan embun humidifier.

scholarly journals Design, additive manufacturing, and performance of heat exchanger with a novel flow-path architecture

2020 ◽  
Vol 180 ◽  
pp. 115775 ◽  
Author(s):  
Adrian S. Sabau ◽  
Adrian Bejan ◽  
David Brownell ◽  
Kyle Gluesenkamp ◽  
Bart Murphy ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Heat Exchanger ◽  
Flow Path ◽  
And Performance

scholarly journals Shear Performance of Optimized-Section Precast Slab with Tapered Cross Section

2018 ◽  
Vol 11 (1) ◽  
pp. 163 ◽  
Author(s):  
Hyunjin Ju ◽  
Sun-Jin Han ◽  
Hyo-Eun Joo ◽  
Hae-Chang Cho ◽  
Kang Kim ◽  
...  
Keyword(s):  
Cross Section ◽  
Design Method ◽  
Precast Concrete ◽  
Bending Moment ◽  
Shear Behaviour ◽  
Element Analysis ◽  
Cross Sectional ◽  
Shear Design ◽  
Shear Performance ◽  
And Performance

The optimized-section precast slab (OPS) is a half precast concrete (PC) slab that highlights structural aesthetics while reducing the quantity of materials by means of an efficient cross-sectional configuration considering the distribution of a bending moment. However, since a tapered cross section where the locations of the top and bottom flanges change is formed at the end of the member, stress concentration occurs near the tapered cross section because of the shear force and thus the surrounding region of the tapered cross section may become unintentionally vulnerable. Therefore, in this study, experimental and numerical research was carried out to examine the shear behaviour characteristics and performance of the OPS with a tapered cross section. Shear tests were conducted on a total of eight OPS specimens, with the inclination angle of the tapered cross section, the presence of topping concrete and the amount of shear reinforcement as the main test variables and a reasonable shear-design method for the OPS members was proposed by means of a detailed analysis based on design code and finite-element analysis.

Analytical Modeling and Performance Study of a Cross Flow Air Dehumidifier Using Liquid Desiccant

2014 ◽  
Vol 875-877 ◽  
pp. 1205-1213 ◽  
Author(s):  
Mohamed M. Bassuoni
Keyword(s):  
Numerical Solutions ◽  
Removal Rate ◽  
Cross Flow ◽  
Operating Conditions ◽  
Maximum Deviation ◽  
Performance Study ◽  
Liquid Desiccant ◽  
Mass Transfer Processes ◽  
And Performance ◽  
Air Conditioning Systems

The dehumidifier is a key component in liquid desiccant air conditioning systems. Various mathematical models of heat and mass transfer processes inside the dehumidifier are introduced and numerically solved in the literature. Analytical solutions have more advantages than numerical solutions in studying the dehumidifier performance parameters. This paper presents the results from an analytical model for the performance of an adiabatic cross flow liquid desiccant air dehumidifier. Calcium chloride is used as desiccant material in this investigation. Both humidity and temperature effectiveness of the dehumidifier are used to predict the performance of the device under various operating conditions. Good accuracy has been found between analytical solution and reliable experimental results with a maximum deviation of +6.63% and -5.65% in the moisture removal rate. The method developed here can be used in the quick prediction of the dehumidifier performance. The exit parameters from the dehumidifier are evaluated under the effects of variables such as air temperature and humidity, desiccant temperature and concentration and air to desiccant flow rates. The results show that hot humid air and desiccant concentration have the greatest impact on the performance of the dehumidifier.

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