Hui Zhang

Hui Zhang
University of California, Berkeley | UCB · Center for the Built Environment

Doctor of Philosophy

About

410
Publications
101,857
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8,664
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Introduction
Dr. Hui Zhang currently works at Center for the Built Environment, University of California, Berkeley. Her research interests cover thermal comfort model, personal comfort system (PCS), and indoor air movement.
Skills and Expertise

Publications

Publications (410)
Article
The spreading behavior of an oil film on an immiscible liquid substrate plays an important role in practical phenomena such as oil spills and thermal spraying. Especially in extremely cold regions such as the Arctic regions, the spreading behavior and balanced state of the spilled oil may be significantly affected due to the varying oil physical pr...
Article
Real-time estimation of the fire status is critical for reliable decision-making in building fire emergencies. Learning-based approaches for fire estimation have achieved great success, benefited from exploration of sensor data. However, existing works are mostly designed for specific building structures and seldom account for false alarms. Such fl...
Article
Full-text available
Thermal comfort is one of the primary factors influencing occupant health, well-being, and productivity in buildings. Existing thermal comfort systems require occupants to frequently communicate their comfort vote via a survey which is impractical as a long-term solution. Here, we present a novel thermal infrared-fused computer vision sensing metho...
Article
Purpose FLASH (ultra-high dose rate) radiotherapy spares normal tissue while keeping tumor control. However, the mechanism of the FLASH effect remains unclear and may have consequences beyond the irradiated area. Materials and Methods We reanalyze the available results of ultra-high-dose-rate-related experiments to find out the key points of the m...
Article
The oxygen transportation from surrounding air to coating cracks is an important factor in the oxidation and ignition of titanium alloy. In this work, the oxygen transport and surface oxidation of titanium in inclined cracks of coating under parallel airflow are studied with the lattice Boltzmann method. A boundary scheme of LBM about surface react...
Article
Full-text available
The depressurization process usually occurs in a cargo compartment when an aircraft is taking off. The fire detection based on the vision-based flame has unique advantages in the confined and inaccessible environment. In this study, the n-heptane pool fires with a diameter of 30 cm were performed in a pressure cabin under decreasing pressure from 1...
Article
Ultra-short, ultra-intense laser facilities could produce ultra-intense pulsed radiation fields. Currently, only passive detectors are fit for dose measurement in this circumstance. Since the laser device could generate a dose up to tens of mSv outside the chamber in tens of picoseconds, resulting in a high instantaneous dose rate of ~107 Sv s-1, i...
Article
A series of pool fires were carried out to study the effect of pool shape and environment pressure on the wall fire behavior. Four sizes of annular pool and three sizes of rectangle pool were used as the oil container. The results showed that the burning rate of both the annular and rectangle pool fire increased with increasing length ratio of the...
Article
The mechanism of the FLASH effect remains unclear and could be revealed by studying chemical reactions during irradiation. Monte Carlo simulation of the radiolytic species is an effective tool to analyze chemical reactions, but the simulation is limited by computing costs of the step-by-step simulation of radiolytic species, especially when conside...
Chapter
This chapter presents an overview of our efforts on solution growth of large-size CdZnTe crystals for X-ray detectors. Firstly, a direct-mixing solution growth (DMSG) method is proposed in order to prepare high-purity CdZnTe crystals from 7N raw material during one single step, and the accelerated crucible rotation technique (ACRT) is used to get l...
Article
Full-text available
Ceiling-fan-integrated air-conditioning (CFIAC) is a concept in which terminal supply ducts and diffusers are replaced by vents/nozzles that jet supply air into the vicinity of ceiling fans to be mixed and distributed within the room. CFIAC distributes the supply air within the room and convectively cools the occupants. This could allow raised ther...
Article
Full-text available
Personal Comfort Systems (PCS) promise to reduce the energy needed to condition indoor environments, while also enhancing their occupants’ thermal pleasure. To explore these potentials in heating conditions, we compared the effectiveness of PCS heating various portions of the occupant against the normal Air Conditioning (AC) practice of warming the...
Article
Full-text available
Rare event search experiments using germanium detectors are performed in underground laboratories to minimize the background induced by cosmic rays. However, the cosmogenic activation of cupreous detector components on the ground generates long half-life radioisotopes and contributes to the background level. We measured cosmogenic activation with 1...
Article
Experiments have reported low normal tissue toxicities during FLASH irradiation, but the mechanism has not been elaborated. Several hypotheses have been proposed to explain the mechanism. One hypothesis is oxygen depletion. We analyze the time-dependent change of oxygen concentration in the tissue to study the oxygen depletion hypothesis using a co...
Article
A two-channel temperature-control CVI scheme was proposed to fabricate thicker and denser composites. The two-channel structure helps to densify a thick preform, and a precise temperature control will guarantee a low and uniform porosity distribution. Validation simulations containing hydrodynamics, mass transfer, heat transfer and pore structure e...
Article
Full-text available
Mathematical and computational models are useful tools for virtual policy experiments on infectious disease control. Most models fail to provide flexible and rapid simulation of various epidemic scenarios for policy assessment. This paper establishes a multi-scale agent-based model to investigate the infectious disease propagation between cities an...
Article
Purpose: Recent studies have suggested that ultra-high dose rate (FLASH) irradiation can spare normal tissues from radiotoxicity, while efficiently controlling the tumor, and this is known as the "FLASH effect". This study performed theoretical analyses to quantitatively investigate the impact of radiolytic oxygen depletion (ROD) on the cellular r...
Article
In a field study conducted in office settings in Sydney, Australia, background survey and right-here-right-now thermal comfort questionnaires were collected from a sample of office workers. Indoor environmental observations, including air temperature, mean radiant temperature, air velocity, and relative humidity, were also recorded and matched with...
Article
Full-text available
Controlled air movement is an effective strategy for maintaining occupant comfort while reducing energy consumption, since comfort at moderately warmer temperatures requires less space cooling. Modern ceiling fans provide a 2–4 °C cooling effect at power consumption comparable to LED lightbulbs (2–30 W) with gentle air speeds (0.5–1 m/s). However,...
Article
Human metabolic rate is a fundamental and essential aspect of thermal comfort, and gender differences in metabolic rate may underlie gender differences in comfort. This study explores gender differences in physiological and subjective responses to a wide range of cold to hot temperatures. Forty healthy college students (20 females and 20 males) par...
Article
Purpose: Research regarding cellular responses at different oxygen concentrations (OCs) is of immense interest within the field of radiobiology. Therefore, this study aimed to develop a mechanistic model to analyze cellular responses at different OCs. Methods: A DNA damage model (the different cell oxygen level DNA damage [DICOLDD] model) that e...
Preprint
Full-text available
The rare event search experiments using germanium detectors are performed in the underground laboratories to prevent cosmic rays. However, the cosmogenic activation of the cupreous detector components on the ground will generate long half-life radioisotopes and contribute continually to the expected background level. We present a study on the cosmo...
Article
The accelerated crucible rotation technique (ACRT) is a widely used method for the optimization of crystal growth. However, the interactions between the original natural convection in the traveling heater method (THM) and forced convection by ACRT make the flow behavior complicated and also hard to be predicted. With the help of numerical simulatio...
Preprint
Purpose: Recent studies suggest ultra-high dose rate (FLASH) irradiation can spare normal tissues from radiotoxicity, while efficiently controlling the tumor, and this is known as the FLASH effect. This study performed theoretical analyses about the impact of radiolytic oxygen depletion (ROD) on the cellular responses after FLASH irradiation. Metho...
Article
The layout of ceiling fans in buildings is challenging because of the need to co-ordinate with other elements in the ceiling space, and because the resulting airflows within the occupied space interact with furniture. This study conducted detailed air speed measurements in four buildings with different room sizes, furniture configurations, ceiling...
Article
Deep transfer learning can make full use of pre-trained neural networks and has been used in many cases with limited sample data. In this work, parameter-transfer learning was implemented to model the relationship between process control parameters and in-flight particle behavior. Six different parameter-transfer learning models were designed to fi...
Preprint
Surveillance cameras are widely applied for indoor occupancy measurement and human movement perception, which benefit for building energy management and social security. To address the challenges of limited view angle of single camera as well as lacking of inter-camera collaboration, this study presents a non-overlapping multi-camera system to enla...
Article
A phosphorus/nitrogen-containing compound (named DOPO-BAPh) was synthesized via the graft reaction between 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and bisphenol A bis(phthalonitrile) containing benzoxazine. The flame retardancy of DOPO-BAPh was investigated on epoxy resin (EP). The results showed that DOPO-BAPh catalyzed the curin...
Article
Fractality is one of the inherent characteristics to present the irregularity and self-similarity of an object. In this study, the fractal theory was applied to the fire scene under decreasing pressure in an aircraft cargo compartment, considering that the compartment is usually inaccessible in flight and flame images are a kind of convenient monit...
Article
The Monte Carlo (MC) simulation is regarded as the gold standard for dose calculation in brachytherapy, but it consumes a large amount of computing resources. The development of heterogeneous computing makes it possible to substantially accelerate calculations with hardware accelerators. Accordingly, this study develops a fast MC tool, called THUBr...
Article
Full-text available
Two multi-exit selection models based on social force model are presented to simulate pedestrian evacuation, and the model coefficients are optimized by considering the effect of the exit distance, exit width, crowd number and distribution. The evacuation processes employing shortest distance evacuation strategy, static and dynamic exit selection m...
Article
Full-text available
Effective fire detection provides early warnings and key information for first responders and people trapped insides. The idea of integrating sensor data and fire modeling presents a general framework for fire source parameter estimation. However, most methods fail to achieve a real-time accurate estimation due to complex building structures and hi...
Article
Safety is vital for people and emergency management helps keep people safe. Emergency management includes four stages: Planning and Mitigation, Preparedness, Response and Recovery. Geospatial applications (including GIS) have been extensively used in each stage of emergency management. Nowadays, on the technical side, artificial intelligence tools...
Article
Safety refers to the stable external environment and orders wherein society and citizens need to engage in and conduct normal life, work, study, entertainment, and communication. Resilience in public safety refers to the ability to withstand the shocks and pressures of emergencies. Emergency management is the creation of plans through which communi...
Article
Full-text available
Solar radiation affects occupant comfort and building energy consumption in ways that have received relatively little attention in environmental design and energy simulation. Direct, diffuse, and reflected irradiation on the body have warming effects that can be equated to increases in the mean radiant temperature (MRT) of the occupant's surroundin...
Article
Indoor carbon dioxide (CO2) is a critical parameter in the design and control of ventilation, and in monitoring fresh air levels in buildings. Building occupants are primary sources for indoors CO2, and the rate at which CO2 is generated depends on the occupants’ physical activities. In the past, CO2 generation rates have been indirectly calculated...
Article
The objective of this work is to study the fire behavior characteristics under low pressures. Cardboard box fire experiments of two kinds of fire load, 1‐box and 2‐box fires, were conducted separately at 101 kPa, 75 kPa, 64 kPa, and 59.5 kPa in an altitude chamber. The heat release rate, mass burning rate, residual ash mass and radiative heat flux...
Preprint
Full-text available
A multilayer perceptron (MLP) neural network is built to analyze the Cs-137 concentration in seawater via gamma-ray spectrums measured by a LaBr3 detector. The MLP is trained and tested by a large data set generated by combining measured and Monte Carlo simulated spectrums under the assumption that all the measured spectrums have 0 Cs-137 concentra...
Preprint
Recently, there has been increasing interest in transparency and interpretability in Deep Reinforcement Learning (DRL) systems. Verbal explanations, as the most natural way of communication in our daily life, deserve more attention, since they allow users to gain a better understanding of the system which ultimately could lead to a high level of tr...
Article
Full-text available
Many experimental studies demonstrated that elevating indoor temperatures to 28 or 30°C is comfortable if fans are used, while this elevation often is not applied in practice. This study aims to investigate AC thermostat use behaviors when elevated air movement is available, as well as to provide insights at guiding occupants to select warmer envir...
Article
Digital and physical prototypes are commonly used across a broad range of industries for product development and user experience testing. Prototyping processes are also used in scientific research to generate ideas and test hypotheses. However, these creative activities receive less attention in research papers than the quantitative methods and fin...
Preprint
Emotion analysis has been attracting researchers' attention. Most previous works in the artificial intelligence field focus on recognizing emotion rather than mining the reason why emotions are not or wrongly recognized. Correlation among emotions contributes to the failure of emotion recognition. In this paper, we try to fill the gap between emoti...
Conference Paper
Full-text available
The estimation of heat release rate (HRR) in a building fire is a meaningful yet challenging task to improve first emergency response. Inspired by the capability of deep learning method that mines patterns from raw data, the inverse model based on Gated Recurrent Unit (GRU) is presented for the inversion of HRR. First, a series of fire scenarios is...
Article
A stable thermal field and a controlled convex growth interface are essential for the stable growth of large-size CdZnTe crystals by the Traveling Heater Method (THM). However, the crucible wall temperature always increases due to the deposition of CdZnTe crystals with low thermal conductivity at the bottom of the crucible. A comprehensive two-dime...
Article
Full-text available
Emotion analysis has been attracting researchers' attention. Most previous works in the artificial-intelligence field focus on recognizing emotion rather than mining the reason why emotions are not or wrongly recognized. The correlation among emotions contributes to the failure of emotion recognition. In this article, we try to fill the gap between...
Article
To improve detection sensitivity for interesting radionuclides in measurements of environmental samples by Broad Energy Germanium detectors, the Pulse Shape Discrimination method using rise-time ratio is introduced. A certified soil sample and a typical squid-ash sample were measured by a well-shielded BEGe spectrometer. Minimum Detection Activitie...
Article
Full-text available
A vertical thermally stratified environment provides opportunities for improved ventilation effectiveness and energy efficiency, but vertical temperature gradient can also cause local thermal discomfort. ASHRAE 55 and ISO 7730 prescribe a 3 °C/m limit between head and feet for seated persons. However, an increasing amount of evidence suggests that...
Article
Full-text available
ASHRAE Standard 55 has been evolving in recent years to encourage more sustainable building designs and operational practices. A series of changes address issues for which past design practice has been deficient or overly constrained. Some of the changes were enabled by findings from field studies of comfort and energy-efficiency, and others by new...
Article
The project goal was to identify and test the integration of smart ceiling fans and communicating thermostats. These highly efficient ceiling fans use as much power as an LED light bulb and have onboard temperature and occupancy sensors for automatic operationbased on space conditions. The Center for the Environment (CBE) at UC Berkeley led the res...
Chapter
Occupants’ behaviors over air-conditioning systems influence building energy consumption to a great extent. It is important to explore occupant use behaviors in buildings. However, when having access to controlling air-conditioning thermostat, and a ceiling fan speed, it is unclear how subjects would control the two cooling strategies. The objectiv...
Article
There are always undesired grains formed at the beginning of unseeded THM growth which deteriorate the crystal quality greatly. In this paper, several ingots with the diameter of 27 mm were grown by unseeded THM to investigate the nucleation process. The growth temperature in the experiments was 750 °C and the growth rate was 5 mm/day. The influenc...
Article
In response to the urgent requirement of material screening in rare event experiments, a new ARray of GermaniUm γ-ray Spectrometer (ARGUS) is planned to be established in China Jinping Underground Laboratory (CJPL). The spectrometer was optimized with Monte Carlo simulation using Geant4. Five HPGe detectors were combined in ARGUS for higher efficie...
Article
Full-text available
Ceiling-Fan-Integrated Air Conditioning (CFIAC) is a proposed system that can greatly increase buildings’ cooling efficiency. In it, terminal supply ducts and diffusers are replaced by vents/nozzles, jetting supply air toward ceiling fans that serve to mix and distribute it within the room. Because of the fans’ air movement, the system provides com...
Article
Full-text available
The ability to inexpensively monitor indoor air speed and direction on a continuous basis would transform the control of environmental quality and energy use in buildings. Air motion transports energy, ventilation air, and pollutants around building interiors and their occupants, and measured feedback about it could be used in numerous ways to impr...
Article
The ring fire usually originates from the combustion of the annular‐distributed fuel, and it may occur in the low‐temperature environments such as the Arctic area and plateau area, which is kind of different from the conventional environment. In this paper, the annular pools with various shape characteristics were designed. The outside diameter ran...
Article
Full-text available
To reduce the seed length while maintaining the advantages of the cuboid KDP-type crystal, a long-seed KDP crystal with size $471~\text{mm}\times 480~\text{mm}\times 400~\text{mm}$ is rapidly grown. With almost the same high cutting efficiency to obtain third harmonic generation oriented samples, this long-seed KDP-type crystal can be grown with a...
Preprint
Background: Experiments have reported low normal tissue toxicities during FLASH radiation, but the mechanism has not been elaborated. Several hypotheses have been proposed to explain the mechanism. The oxygen depletion hypothesis has been introduced and mostly studied qualitatively. Methods: We present a computational model to describe the time-dep...
Article
The influences of shape characteristics and pressure on n-Heptane ring fire were investigated through two groups of experiments. In group A, the ring fire with varying shape characteristics was conducted. In group B, the ring fire was performed under sub-atmospheric pressures including 45 kPa, 60 kPa, 75 kPa, and 90 kPa. The results show that the m...
Article
During exercise, comfort requirements are different because of the elevated metabolic heat production. It is essential to know the preferable thermal environment to give environmental design suggestions to sports facilities. Experimental studies on preferred temperature were conducted on 20 healthy human subjects walking on a treadmill at 4, 5, and...
Article
To solve the limitation of the fire test in high‐altitude areas only detecting a limited number of low‐pressure environments, in this paper, appropriate modifications of the FDS source codes were made to generate a new simulator program for low‐pressure applications. Standard fire experiments with different counts (1, 2, 18, and 27) of cardboard bo...