BALANCING TRADE-OFFS IN ONE-STAGE PRODUCTION WITH PROCESSING TIME UNCERTAINTY

Stochastic production scheduling faces three challenges, first the inconsistencies among key performance indicators (KPIs), second the trade-offs between the expected return and the risk for a portfolio of KPIs, and third the uncertainty in processing times. Based on two inconsistent KPIs of total completion time (TCT) and variance of completion times (VCT), we propose our trade-off balancing (ToB) heuristic for one-stage production scheduling. Through comprehensive case studies, we show that our ToB heuristic with preference =0.0:0.1:1.0 efficiently and effectively addresses the three challenges. Moreover, our trade-off balancing scheme can be generalized to balance a number of inconsistent KPIs more than two. Daniels and Kouvelis (DK) proposed a scheme to optimize the worst-case scenario for stochastic production scheduling and proposed the endpoint product (EP) and endpoint sum (ES) heuristics to hedge against processing time uncertainty. Using 5 levels of coefficients of variation (CVs) to represent processing time uncertainty, we show that our ToB heuristic is robust as well, and even outperforms the EP and ES heuristics on worst-case scenarios at high levels of processing time uncertainty. Moreover, our ToB heuristic generates undominated solution spaces of KPIs, which not only provides a solid base to set up specification limits for statistical process control (SPC) but also facilitates the application of modern portfolio theory and SPC techniques in the industry

Discovery of novel potential protein diagnostic biomarkers for prostate cancer in serum and tears

Prostate cancer (CaP) is a heterogeneous multifocal cancer with high prevalence worldwide, particularly in developed countries. The introduction of the prostate specific antigen (PSA) blood test for CaP diagnosis saw a dramatic increase in the reported incidence rate of CaP, but only a slight decrease in mortality, highlighting the importance of developing a more accurate CaP diagnostic test. Discovery of novel biomarkers has been the focus of cancer diagnostic research, with protein biomarkers of particular relevance due to their direct reflection of phenotype changes, resulting from pathophysiological conditions and their presence in the easy accessible body fluids. The aim of this PhD project was to detect, identify and verify potential novel CaP specific protein biomarkers that could distinguish CaP from benign prostatic hyperplasia (BPH) and healthy control groups; ideally identifying novel molecules that have the potential to improve the screening accuracy of the current CaP diagnostic test. Serum and tears were used as the sources of biomarkers in this study. As a circulatory body fluid, serum can reflect the molecular changes due to the presence of CaP. The tear film is of particular interest in CaP research, as both the prostate gland and the major tear producing gland, the lacrimal gland, are androgen regulated. Various proteomic approaches including gel based, mass spectrometry based and targeted antibody based techniques were used in this study to examine the serum and tear proteomes as well as for protein identification and quantitation. The key finding of the present study was the identification of five serum proteins (albumin, fetuin A, IGHM, hemopexin and C4BPA) and one peptide (VPSHAVVAR) derived from the tear protein, lactoferrin, as potential biomarkers for CaP. From these proteins, albumin and fetuin A were evaluated in a separate small sample group of subjects, with these results further indicating their potential for differentiating between CaP and control groups. Moreover, this was also the first study which has used MRM to validate presence of a novel tear protein dermcidin, to relatively quantify six tear proteins and to detect a potential CaP biomarker peptide in tears. The findings from this study suggest that, using larger sample size to verify the results presented, the development of more accurate and non-invasive clinical tests for the diagnosis of CaP may be possible

Models for 31-Mode PVDF Energy Harvester for Wearable Applications

Currently, wearable electronics are increasingly widely used, leading to an increasing need of portable power supply. As a clean and renewable power source, piezoelectric energy harvester can transfer mechanical energy into electric energy directly, and the energy harvester based on polyvinylidene difluoride (PVDF) operating in 31-mode is appropriate to harvest energy from human motion. This paper established a series of theoretical models to predict the performance of 31-mode PVDF energy harvester. Among them, the energy storage one can predict the collected energy accurately during the operation of the harvester. Based on theoretical study and experiments investigation, two approaches to improve the energy harvesting performance have been found. Furthermore, experiment results demonstrate the high accuracies of the models, which are better than 95%

Fault Diagnosis in a Gyroscope-Based Six-Axis Accelerometer

An investigation into the fault diagnosis of a six-axis accelerometer is of great significance because of the high reliability requirement in areas such as aerospace. The working principle and decoupling algorithm of a six-axis accelerometer are introduced. The six-axis accelerometer and the gyroscope form the measurement system and provide the basis for fault diagnosis and restoration by deriving force and deformation compatibility equations. Descartes three-dimensional coordinate system of fault diagnosis is put forward, which carries out the function of real-time diagnosis of the measurement system. In view of a specific fault case, restoration was performed by replacing fault data of a branch chain with correct data. A relevant experiment was carried out and the results confirm the effectiveness of the restoration

INFLUENCES ANALYSIS OF CONFIGURATIONS ON THE PERFORMANCE OF PARALLEL TYPE SIX-AXIS ACCELEROMETERS

The development of parallel type six-axis accelerometers was hindered for their complicated forward kinematics and dynamics algorithms which make it difficult to decouple the six acceleration components timely, accurately and stably. This paper applies four parallel configurations with 6-DOF and a closed-form solution of the forward kinematics to six-axis accelerometers as the elastic bodies, where the piezoelectric ceramics act as the sensitive elements and play the role of prismatic pairs. An efficient decoupling algorithm was derived to calculate the six acceleration components completely by the use of Kane’s dynamics method in configuration space. Considering the differences in sensing properties of the four six-axis accelerometers, a quantitative comparison was conducted to reveal the configurations’ direct influences on some static characteristics, including accuracy, efficiency, sensitivity, isotropy, and working frequency range, which makes a theoretical foundation for the subsequent design of a reconfigurable prototype

INFLUENCES ANALYSIS OF CONFIGURATIONS ON THE PERFORMANCE OF PARALLEL TYPE SIX-AXIS ACCELEROMETERS

The development of parallel type six-axis accelerometers was hindered for their complicated forward kinematics and dynamics algorithms which make it difficult to decouple the six acceleration components timely, accurately and stably. This paper applies four parallel configurations with 6-DOF and a closed-form solution of the forward kinematics to six-axis accelerometers as the elastic bodies, where the piezoelectric ceramics act as the sensitive elements and play the role of prismatic pairs. An efficient decoupling algorithm was derived to calculate the six acceleration components completely by the use of Kane’s dynamics method in configuration space. Considering the differences in sensing properties of the four six-axis accelerometers, a quantitative comparison was conducted to reveal the configurations’ direct influences on some static characteristics, including accuracy, efficiency, sensitivity, isotropy, and working frequency range, which makes a theoretical foundation for the subsequent design of a reconfigurable prototype

Differential Modulation for Short Packet Transmission in URLLC

One key feature of ultra-reliable low-latency communications (URLLC) in 5G is to support short packet transmission (SPT). However, the pilot overhead in SPT for channel estimation is relatively high, especially in high Doppler environments. In this paper, we advocate the adoption of differential modulation to support ultra-low latency services, which can ease the channel estimation burden and reduce the power and bandwidth overhead incurred in traditional coherent modulation schemes. Specifically, we consider a multi-connectivity (MC) scheme employing differential modulation to enable URLLC services. The popular selection combining and maximal ratio combining schemes are respectively applied to explore the diversity gain in the MC scheme. A first-order autoregressive model is further utilized to characterize the time-varying nature of the channel. Theoretically, the maximum achievable rate and minimum achievable block error rate under ergodic fading channels with PSK inputs and perfect CSI are first derived by using the non-asymptotic information-theoretic bounds. The performance of SPT with differential modulation and MC schemes is then analysed by characterizing the effect of differential modulation and time-varying channels as a reduction in the effective SNR. Simulation results show that differential modulation does offer a significant advantage over the pilot-assisted coherent scheme for SPT, especially in high Doppler environments.Comment: 15 pages, 9 figure