Thermal stresses and temperature control of mass concrete

... Thermal Stresses and Temperature Control of Mass Concrete Thermal Stresses and Temperature Control of Mass Concrete Zhu Bofang China Institute of Water Resources and Hydropower Research and ... of thermal stress and temperature control of mass concrete, including two basic theorems of creep of nonhomogeneous concrete structures, the l...

Ngày tải lên: 21/04/2015, 13:38

... Gravity and Absorption of Fine Aggregate BATCHING, MIXING, AND JOB CONTROL OF LIGHTWEIGHT CONCRETE C 138 C 143 C 172 C 173 C 231 C 330 C 567 Standard Test Method for Unit Weight, Yield, and Air ... changes in the amount of water needed to produce the desired slump 3.2.1 Transportation and waiting time Construction BATCHING, MIXING, AND JOB CONTROL OF LIG...

Ngày tải lên: 24/10/2014, 17:44

... of adiabatic temperature rise and reaction velocity by classification of binder quantity 3.2 Temperature rise quantity and analysis of Mock-up Test The time reaching the highest temperature of ... measured and analyzed (Center) The measured results (Center) Table The amount of adiabatic temperature rise and reaction velocity of the real member Class Temp...

Ngày tải lên: 07/03/2014, 03:20

... from restraint of thermal contraction A detailed discussion of the effects of heat generation and volume changes on the design and behavior of mass reinforced concrete elements and structures ... generation The rate and magnitude of heat generation of the concrete depends on the amount per unit volume of cement and pozzolan (if any), the compound composit...

Ngày tải lên: 24/10/2014, 17:26

... 133.7 128 .5 128 .5 128 .5 change to 129 .6 128 .5 change to 129 .5 2. 12 2. 12 1. 52 1.53 1.98 1.98 1.70 1.71 401 398 400 399 400 400 399 400 1 128 .2 128 .2 128 .2 128 .2 126 .6 126 .6 126 .6 126 .6 23 140 120 ... to 133.6 130 130 128 .5 128 .5 change to 129 .6 2. 13 1.54 2. 12 1.54 1.98 1.73 1.98 1.70 399 3 62 399 400 422 408 400 401 23 46 1 128 .1 125 .4 128 .2 128 .2 128...

Ngày tải lên: 10/09/2015, 15:48

... during initial period of wood drying Model Model o Temperature ( C) 58 54 50 46 1. 00 1. 01 1.03 1. 04 1. 05 1. 06 1. 08 1. 09 1. 10 1. 12 Distance from centre (mm) (Graph taken from Zhang and Datta (2004), ... self -heating of wood chars 1. 3 Scope of work Taking into consideration of the above objectives, the focus of this thesis is on thermal combustion a...

Ngày tải lên: 14/09/2015, 14:14

... primary wood degradation mechanisms of such description is based on Shafizadeh and Chin (1977) work which expresses the decomposition as k1 WOOD → TAR (2. 22) k2 WOOD → GAS (2. 23) k3 WOOD → CHAR (2. 24) ... exp(− K / Ts ) pv , sat where K1 and (2. 8) K are constants which depend on the temperature range, and K1 4.143 ×1010 Pa and K = 4 822 K in the temperature range of...

Ngày tải lên: 14/09/2015, 14:14

... and erratic velocity profile   S-curve temperature profile  COUPLED VELOCITY AND TEMPERATURE DEVELOPMENT IN SELF -HEATING Figure 3. 1: Salient features of porous models for low- temperature long- term ... a factor of has been applied onto the porosity of green wood to derive the porosity of preburn wood, since pre-burn wood in this study has a 50% degree of...

Ngày tải lên: 14/09/2015, 14:14

... λ s λ (4. 47) Substituting Equations (4. 46) and (4. 47) into Equation (4. 45) yields C1 as C1 = Substituting Equation (4. 48) and H =  ′′ qe (4. 48)  s  + h s k  λ  h into Equation (4. 46), then ... 10 644 6 24 640 640 636 6 24 708 652 628 6 64 External heat flux &e q′′ (kW m-2) 50a 40 a 30a 25a 20a 15b 11c 10c 9c 8c Time to ignition tig (hr:min:s) 0:0:26 0:0: 54 0:1 :48 0:...

Ngày tải lên: 14/09/2015, 14:14

... a ratio of 1:100 (see Figures 5. 5 and 5. 6.) Discs 12.7 mm diameter and mm thick (see Figures 5. 7 and 5. 8) were pressed in a vacuum KBr press (Perkin-Elmer) at 100,000 psi Figure 5. 5 Wood samples ... grinding the wood discs sliced from the wood blocks and sieved to the desired particle size of 200 to 300 μm The wood powders were stored at 50 %RH at 23°C in a...

Ngày tải lên: 14/09/2015, 14:14

... 6. 2 Heat and mass transfer in porous slab Self -heating and spontaneous combustion of wood was studied using wood cube of critical size exposed to low- temperature, long- term heating in an isothermal ... 25 20 15 11 10 26 54 108 324 764 3222 7990 7554 463 .01 465 .70 431. 06 4 36. 06 402. 16 367 .60 315. 26 298.38 266 .5 373.4 374.9 375.9 373.9 460 .5 345.4 3...

Ngày tải lên: 14/09/2015, 14:14

... the body of knowledge on thermal combustion and oxygen chemisorption of wood in the following areas: evaporation, liquid water transport, role of moisture in thermal combustion and oxygen chemisorption ... addition to thermophysical approach to examine self -heating and spontaneous combustion of low- temperature, long- term preheated wood, targeted...

Ngày tải lên: 14/09/2015, 14:14

... develop a controller for temperature control inside a room within a desired band of temperatures for comfort The details of the geometry of the room and the HVAC system based on displacement ventilation ... disadvantages of the DMC controller First, the DMC controller is a local controller which can only guarantee the stability of the...

Ngày tải lên: 05/09/2013, 16:11

... P a g e Simulation and Speed Control of Induction Motor Drives 2012 CHAPTER ANALYSIS OF VARIOUS METHODS FOR SPEED CONTROL OF IM The various methods of speed control of 3- Induction motor are ... Simulation and Speed Control of Induction Motor Drives 2012 Figure 3.13: Torque -Speed Characteristics for machine parameters as in Fig 3.8 13 | P...

Ngày tải lên: 18/12/2013, 22:06

... therefore in this paper a new transformation which preserves the same advantages as the Park transformation A Mathematical Model of the BDCM We suppose that the motor has the following typical features ... pulsating torque (the homopolar part) and a two-phase motor with a rotating field (the "ap" The classical Park transformation is, in fact, the succ...

Ngày tải lên: 03/01/2014, 19:44