Xiaojun Zhai

University of Essex · School of Computer Science and Electronic Engineering

Osteoporosis, a significant concern among the elderly, results in low-trauma fractures affecting millions globally. Despite the inclusion of physical activities in strategies to mitigate osteoporosis-related fractures, the optimal exercises for bone health remain uncertain. Determining exercises that enhance bone mass requires an understanding of l...

High amplitudes of shock during running have been thought to be associated with an increased injury risk. This study aimed to quantify the association between dual-energy X-ray absorptiometry (DEXA) quantified body composition, and shock attenuation across the time and frequency domains. Twenty-four active adults participated. A DEXA scan was perfo...

Building prediction models using biomechanical features is challenging because such models may require large sample sizes. However, collecting biomechanical data on large sample sizes is logistically very challenging. This study aims to investigate if modern machine learning algorithms can help overcome the issue of limited sample sizes on developi...

Unmanned Surface Vehicles (USVs) in inland waterways have drawn increasing attention for their excellent capability to serve maritime time-consuming missions such as autonomous navigation and intelligent monitoring. However, USVs struggle to accomplish emerging computation-intensive tasks (e.g., sensor, telemetry, etc) timely due to the limited on-...

Nowadays, an Electronic Toll Collection (ETC) control system in highways has been widely adopted to smoothen traffic flow. However, as it is a complex business interaction system, there are inevitably flaws in its control logic process, such as the problem of vehicle fee evasion. Even we find that there are more than one way for vehicles to evade f...

DNA methylation (DNAm)-based age clocks have been studied extensively as a biomarker of human ageing and a risk factor for age-related diseases. Despite different tissues having vastly different rates of proliferation, it is still largely unknown whether they age at different rates. It was previously reported that the cerebellum ages slowly; howeve...

Joint moment measurements represent an objective biomechemical parameter in joint health assessment. Inverse dynamics based on 3D motion capture data is the current 'gold standard’ to estimate joint moments. Recently, machine learning combined with data measured by wearable technologies such electromyography (EMG), inertial measurement units (IMU),...

Deep Neutral Networks (DNNs) have been widely used in many applications, such as self-driving cars, natural language processing (NLP), image classification, visual object recognition, and so on. Field-programmable gate array (FPGA) based Multiprocessor System on a Chip (MPSoC) is recently considered one of the popular choices for deploying DNN mode...

Alterations in joint contact forces (JCFs) are thought to be important mechanisms for the onset and progression of many musculoskeletal and orthopaedic pain disorders. Computational approaches to JCFs assessment represent the only non-invasive means of estimating in-vivo forces; but this cannot be undertaken in free-living environments. Here, we us...

The application of machine learning-based tele-rehabilitation faces the challenge of limited availability of data. To overcome this challenge, data augmentation techniques are commonly employed to generate synthetic data that reflect the configurations of real data. One such promising data augmentation technique is the Generative Adversarial Networ...

All-dielectric terahertz metasurface absorbers have aroused widespread attention over the past few years for their flexible design concepts and excellent absorbing properties. However, the existing all-dielectric terahertz metasurface absorbers are subjected to poor tunability. In this study, a high-efficiency magnetically tunable terahertz all-die...

With the rapid spread of e-commerce and e-payment, the increasing number of people choose online shopping instead of traditional buying way. However, the malicious user behaviors have a significant influence on the security of users' accounts and property. In order to guarantee the security of shopping environment, a method based on Complex Event P...

Gait analysis plays an important role in the fields of healthcare and sports sciences. Conventional gait analysis relies on costly equipment such as optical motion capture cameras and wearable sensors, some of which require trained assessors for data collection and processing. With the recent developments in computer vision and deep neural networks...

Visual Place Recognition has recently seen a surge of endeavours utilizing different ensemble approaches to improve VPR performance. Ideas like multi-process fusion or switching involve combining different VPR techniques together, utilizing different strategies. One major aspect often common to many of these strategies is voting. Voting is widely u...

Deep neural networks (DNNs) are a key technique in modern artificial intelligence that has provided state-of-the-art accuracy on many applications, and they have received significant interest. The requirements for ubiquity of smart devices and autonomous robot systems are placing heavy demands on DNNs-inference hardware, with high requirement for e...

Improving result-accuracy in approximate computing (AC) based real-time applications without violating deadline has recently become an active research domain. Execution-time of AC real-time tasks can individually be separated into: execution of the mandatory part to obtain a result of acceptable quality, followed by a partial/complete execution of...

It is important to understand the process of cancer cell metastasis and some cancer characteristics that increase disease risk. Because the occurrence of the disease is caused by many factors, and the pathogenesis process is also complicated. It is necessary to use interpretable and visual modeling methods to characterize this complex process. Mach...

Motivation Data normalization is an essential step to reduce technical variation within and between arrays. Due to the different karyotypes and the effects of X chromosome inactivation, females and males exhibit distinct methylation patterns on sex chromosomes, thus it poses a significant challenge to normalise sex chromosome data without introduci...

The emergence of new nanoscale technologies has imposed significant challenges to designing reliable electronic systems in radiation environments. A few types of radiation like Total Ionizing Dose (TID) can cause permanent damages on such nanoscale electronic devices, and current state-of-the-art technologies to tackle TID make use of expensive rad...

It is of vital importance to accurately monitor post-stroke and one common way is to use wearable sensors to collect data and apply Convolutional Neural Networks (CNNs) to process it. In this paper a pipeline for TS classification is evaluated on a complex dataset which comprises 18 different ADLs collected from inertial measurement units sensors....

Background DNA methylation (DNAm) based age clocks have been studied extensively as a biomarker of human ageing and risk factor for age-related diseases. Despite different tissues having vastly different rates of proliferation, it is still largely unknown whether they age at different rates. It was previously reported that the cerebellum ages slowl...

Knee joint moments are commonly calculated to provide an indirect measure of knee joint loads. A shortcoming of inverse dynamics approaches is that the process of collecting and processing human motion data can be time-consuming. This study aimed to benchmark five different deep learning methods in using walking segment kinematics for predicting in...

When electronic systems are working in radiation environments, transient errors, and permanent errors may occur. Static random-access memory (SRAM) has been the one of most significant parts in various semiconductor chips for its high performance and high logic density features. However, because of their dedicated electronic circuits, SRAMs are sen...

Snow coverage mapping plays a vital role not only in studying hydrology and climatology, but also in investigating crop disease overwintering for smart agriculture management. This work investigates snow coverage mapping by learning from Sentinel-2 satellite multispectral images via machine-learning methods. To this end, the largest dataset for sno...

The emergence of new nanoscale technologies has imposed significant challenges to designing reliable electronic systems in radiation environments. A few types of radiation like Total Ionizing Dose (TID) effects often cause permanent damages on such nanoscale electronic devices, and current state-of-the-art technologies to tackle TID make use of exp...

A cerebrovascular accident or stroke is the second commonest cause of death in the world. If it is not fatal, it can result in paralysis, sensory impairment and significant disability. Rehabilitation plays an important role to help survivors relearn lost skills and assist them to regain independence and thus ameliorate their quality of life. With t...

Accurate weed mapping is a prerequisite for site-specific weed management to enable sustainable agriculture. This work aims to analyse (spectrally) and mapping blackgrass weed in wheat fields by integrating Unmanned Aerial Vehicle (UAV), multispectral imagery and machine learning techniques. 18 widely-used Spectral Indices (SIs) are generated from...

The emerging field of flexible bio-mechatronic technologies, such as wearable sensors, actuators and robots, are playing more and more crucial roles in the design and development of next generation healthcare and rehabilitation systems that safely and smartly interact with human patients. To create a complex and intelligent healthcare and rehabilit...

The recent COVID-19 pandemic has further high-lighted the need for improving tele-rehabilitation systems. One of the common methods is to use wearable sensors for monitoring patients and intelligent algorithms for accurate and objective assessments. An important part of this work is to develop an efficient evaluation algorithm that provides a high-...

Joint moments are commonly calculated in biomechanics research and provide an indirect measure of muscular behaviors and joint loads. However, joint moments cannot be easily quantified clinically or in the field, primarily due to challenges measuring ground reaction forces outside the laboratory. The present study aimed to compare the accuracy of t...

Motivation Data normalization is an essential step to reduce technical variation within and between arrays. Due to the different karyotypes and the effects of X chromosome inactivation, females and males exhibit distinct methylation patterns on sex chromosomes, thus it poses a significant challenge to normalise sex chromosome data without introduci...

All-Programmable System-on-Chips (APSoCs) constitute a compelling option for employing applications in radiation environments thanks to their high-performance computing and power efficiency merits. Despite these advantages, APSoCs are sensitive to radiation like any other electronic device. Processors embedded in APSoCs, therefore, have to be adequ...

Internet-of-Things (IoT) is an appealing service to revolutionise Smart City (SC) initiatives across the globe. IoT interconnects a plethora of digital devices known as Sensor Nodes (SNs) to the Internet. Due to their high performance and exceptional Quality-of-Service (QoS) Multiprocessor System-on-Chip (MPSoC) computing architectures are gaining...

Malaria is an important and worldwide fatal disease that has been widely reported by the World Health Organization (WHO), and it has about 219 million cases worldwide, with 435,000 of those mortal. The common malaria diagnosis approach is heavily reliant on highly trained experts, who use a microscope to examine the samples. Therefore, there is a n...

Background Sex is an important covariate of epigenome-wide association studies due to its strong influence on DNA methylation patterns across numerous genomic positions. Nevertheless, many samples on the Gene Expression Omnibus (GEO) frequently lack a sex annotation or are incorrectly labelled. Considering the influence that sex imposes on DNA meth...

This paper proposes an energy efficient real-time scheduling strategy called EnSuRe, which (i) executes real-time tasks on low power consuming primary processors to enhance the system accuracy by maintaining the deadline and (ii) provides reliability against a fixed number of transient faults by selectively executing backup tasks on high power cons...

Field-programmable gate arrays (FPGAs) offer the flexibility of general-purpose processors along with the performance efficiency of dedicated hardware that essentially renders it as a platform of choice for modern-day robotic systems for achieving real-time performance. Such robotic systems when deployed in harsh environments often get plagued by f...

The transistor simulation tools (e.g. TCAD and SPICE) are widely used to simulate single event effects (SEE) in industry. However, due to the variances of the physical parameters in practical design, e.g. the nature of the particle, linear energy transfer and circuit characteristics would have a large impacts on the final simulation accuracy, which...

There is an increasing desire to conduct autonomous inspection of nuclear sites using robots. However, the presence of gamma radiation in nuclear sites induces degradation in vision sensors. In this paper, the effects of gamma radiation on a robot vision sensor (CMOS camera) used for radiological inspection is examined. The analyses have been carri...

Sex is an important covariate of epigenome-wide association studies due to its strong influence on DNA methylation patterns across numerous genomic positions. Nevertheless, many samples on the Gene Expression Omnibus (GEO) frequently lack a sex annotation or are incorrectly labelled. Considering the influence that sex imposes on DNA methylation pat...

An attractive option for realizing applications in radiation environments is to employ All-Programmable System-on-Chips (APSoCs) thanks to their high-performance computing and power efficiency merits. Despite APSoC’s advantages, like any other electronic device, they are prone to radiation effects. Processors found in APSoCs must, therefore, be ade...

Robots can be used to deal with hazardous materials like nuclear waste. Unfortunately, electronic components are also susceptible to radiation effects. Current proposals to tackle this issue solve only parts of the problems for the specific scenarios and the specific types of radiation. At the same time, current computational devices should provide...

As one of the most important components in the embedded systems, the SRAM are sensitive to radiation effects. When the embedded systems working in the extreme radiation environments, the bit flips could occur frequently and decrease the reliability of the systems significantly. In this paper, the self-scrubbing RAM scheme is proposed for light wigh...

Wireless sensor network (WSN) consists of a large number of sensor nodes distributed over a certain target area. The WSN plays a vital role in surveillance, advanced healthcare, and commercialized industrial automation. Enhancing energy-efficiency of the WSN is a prime concern because higher energy consumption restricts the lifetime (LT) of the net...

PurposeCerebral aneurysms are one of the prevalent cerebrovascular disorders in adults worldwide and caused by a weakness in the brain artery. The most impressive treatment for a brain aneurysm is interventional radiology treatment, which is extremely dependent on the skill level of the radiologist. Hence, accurate detection and effective therapy f...

Recently, coronary heart disease has attracted more and more attention, where segmentation and analysis for vascular lumen contour are helpful for treatment. And intravascular optical coherence tomography (IVOCT) images are used to display lumen shapes in clinic. Thus, an automatic segmentation method for IVOCT lumen contour is necessary to reduce...

Soft-core processors implemented in SRAM-based FPGAs are an attractive option for applications to be employed in radiation environments due to their flexibility, relatively-low application development costs, and reconfigurability features enabling them to adapt to the evolving mission needs. Despite the advantages soft-core processors possess, they...

In the last five years or so, there has been a great interest in RF OAM to address the contradiction between the lack of wireless spectrum resources and the continually growing demands of the bandwidth. Recent developments and technological advancements in antenna design, material science, and integrated circuits have enabled miniaturized, multiple...

Orbital angular momentum (OAM) beam emitters with compact structure and high performance are highly desirable for wireless communication and radar technology. Here, we propose a compact emitter that only consists of a ring resonator and a feed line. Continuously-variable-mode OAM beams are generated by adjusting the wavelength and transmission path...

Cerebral aneurysm is a cerebrovascular disorder caused by a weakness in the wall of an artery or vein, which causes a localized dilation or ballooning of the blood vessel. It is life-threatening; hence, an early and accurate diagnosis would be a great aid to medical professionals in making the correct choice of treatment. HemeLB is a massively para...

Automatic number plate recognition (ANPR) systems have become widely used in safety, security, and commercial aspects. A typical ANPR system consists of three main stages: number plate localization (NPL), character segmentation (CS), and optical character recognition (OCR). In recent years, to provide a better recognition rate, high-definition (HD)...

Malaria, a not only widespread but also a potentially fatal disease that can be found mainly in tropical regions of the world, with the World Health Organization reporting an estimated 219 million cases worldwide as of 2017 of which 435,000 were mortal. Diagnosis currently involves taking a blood sample from a patient who is presumed to be infected...

Nowadays, with the phenomenon of the world ageing getting serious, the demand for intelligent medical treatment becomes higher than past. A series of smart bracelets have been launched for the health of the elderly, which can detect the health condition of the elderly in real-time. When an abnormal phenomenon occurs and the rescue will be needed, i...

Electromagnetic waves carrying an orbital angular momentum (OAM) are of great interest. However, most OAM antennas present disadvantages such as a complicated structure, low efficiency, and large divergence angle, which prevents their practical applications. So far, there are few papers and research focuses on the problem of the divergence angle. H...

Violence detection is becoming increasingly relevant in many areas such as for automatic content filtering, video surveillance and law enforcement. Existing datasets and methods discriminate between violent and non-violent scenes based on very abstract definitions of violence. Available datasets, such as “Hockey Fight” and “Movies”, only contain fi...

The interlinked processing units in modern Cyber-Physical Systems (CPS) creates a large network of connected computing embedded systems. Network-on-Chip (NoC)-based Multiprocessor System-on-Chip (MPSoC) architecture is becoming a de facto computing platform for real-time applications due to its higher performance and Quality-of-Service (QoS). The n...

A weakness in the wall of a cerebral artery causing a dilation or ballooning of the blood vessel is known as a cerebral aneurysm. Optimal treatment requires fast and accurate diagnosis of the aneurysm. HemeLB is a fluid dynamics solver for complex geometries developed to provide neurosurgeons with information related to the flow of blood in and aro...

Soft errors are one of the significant design technology challenges at smaller technology nodes and especially in radiation enviro nments. This paper presents a particular class of approaches to provide reliability against radiation-induced soft errors. The paper provides a review of the lockstep mechanism across different levels of design abstract...

PhotoDNA is a perceptual fuzzy hash technology designed and developed by Microsoft. It is deployed by all major big data service providers to detect Indecent Images of Children (IIOC). Protecting the privacy of individuals is of paramount importance in such images. Microsoft claims that a PhotoDNAhash cannot be reverse engineered into the original...

Nowadays, modern communication system relies on the designs of high-performance devices to enhance communication effect for high quality of life and smart city system. As a crucial signal processing step, microwave filter removes unwanted frequency components away from the received signal and enhances the useful ones. However, large loss, bulky siz...

Background and objectives Surgical procedures such as laparoscopic and robotic surgeries are popular since they are invasive in nature and use miniaturized surgical instruments for small incisions. Tracking of the instruments (graspers, needle drivers) and field of view from the stereoscopic camera during surgery could further help the surgeons to...

A weakness in the wall of a cerebral artery causing a dilation or ballooning of the blood vessel is known as a cerebral aneurysm. Optimal treatment requires fast and accurate diagnosis of the aneurysm. HemeLB is a fluid dynamics solver for complex geometries developed to provide neurosurgeons with information related to the flow of blood in and aro...

The increasing use of social media networks on handheld devices, especially smartphones with powerful built-in cameras, and the widespread availability of fast and high bandwidth broadband connections, added to the popularity of cloud storage, is enabling the generation and distribution of massive volumes of digital media, including images and vide...

Cloud datacentres are turning out to be massive energy consumers and environment polluters, which necessitate the need for promoting sustainable computing approaches for achieving environment-friendly datacentre execution. Direct causes of excess energy consumption of the datacentre include running servers at low level of workloads and over-provisi...

Mobile robots can effectively coordinate information among sensor nodes in a distributed physical proximity. Accurately locating the mobile robots in such a distributed scenario is an important requirement, such that mobile robots can be instructed to coordinate with appropriate sensor nodes. Packet loss is one of the prevailing issues in such wire...

Cerebral aneurysm is a life‐threatening condition. It is a weakness in a blood vessel that may enlarge and bleed into the surrounding area. In order to understand the surrounding environmental conditions during the interventions or surgical procedures, a simulation of blood flow in cerebral arteries is needed. One of the effective simulation approa...

The Internet of Things (IoT) has started redesigning the paradigm of the connected health sector by leveraging the availability of low power, low-cost sensors and efficient communication protocols. Consequently, IoT based connected health platforms are expected to further enhance the patient connectivity and everyday convenience. Nevertheless, issu...