Design and Analysis of Multiple-Load Automated Guided Vehicle Dispatching Algorithms

This paper addresses the problems of dispatching multiple-load automated guided vehicles (AGVs) in flexible manufacturing systems (FMSs). A pickup-or-delivery-en-route (PDER) rule is proposed to address the task-determination problem that indicates if a partially loaded AGV’s next task should be picking up a new job or dropping off a carried load. A workload-balancing (WLB) algorithm is developed to deal with the pickup-dispatching problem that determines which job should be assigned to an AGV. A simulation experiment is conducted to compare the PDER rule with an existing task-determination rule in 2 representative FMSs. We use another simulation experiment to compare the WLB rule with 4 existing pickup-dispatching rules in 3 FMSs. The results show that the PDER rule can significantly improve the system throughput and reduce the average time in system of parts, while the WLB rule also has an outstanding throughput performance

Task Assignment and Path Planning for Autonomous Mobile Robots in Stochastic Warehouse Systems

The material handling industry is in the middle of a transformation from manual operations to automation due to the rapid growth in e-commerce. Autonomous mobile robots (AMRs) are being widely implemented to replace manually operated forklifts in warehouse systems to fulfil large shipping demand, extend warehouse operating hours, and mitigate safety concerns. Two open questions in AMR management are task assignment and path planning. This dissertation addresses the task assignment and path planning (TAPP) problem for autonomous mobile robots (AMR) in a warehouse environment. The goals are to maximize system productivity by avoiding AMR traffic and reducing travel time. The first topic in this dissertation is the development of a discrete event simulation modeling framework that can be used to evaluate alternative traffic control rules, task assignment methods, and path planning algorithms. The second topic, Risk Interval Path Planning (RIPP), is an algorithm designed to avoid conflicts among AMRs considering uncertainties in robot motion. The third topic is a deep reinforcement learning (DRL) model that is developed to solve task assignment and path planning problems, simultaneously. Experimental results demonstrate the effectiveness of these methods in stochastic warehouse systems

KF-Loc: A Kalman Filter and Machine Learning Integrated Localization System Using Consumer-Grade Millimeter-wave Hardware

With the ever-increasing demands of e-commerce, the need for smarter warehousing is increasing exponentially. Such warehouses requires industry automation beyond Industry 4.0. In this work, we use consumer-grade millimeter-wave (mmWave) equipment to enable fast, and low-cost implementation of our localization system. However, the consumer-grade mmWave routers suffer from coarse-grained channel state information due to cost-effective antenna array design limiting the accuracy of localization systems. To address these challenges, we present a Machine Learning (ML) and Kalman Filter (KF) integrated localization system (KF-Loc). The ML model learns the complex wireless features for predicting the static position of the robot. When in dynamic motion, the static ML estimates suffer from position mispredictions, resulting in loss of accuracy. To overcome the loss in accuracy, we design and integrate a KF that learns the dynamics of the robot motion to provide highly accurate tracking. Our system achieves centimeter-level accuracy for the two aisles with RMSE of 0.35m and 0.37m, respectively. Further, compared with ML only localization systems, we achieve a significant reduction in RMSE by 28.5% and 54.3% within the two aisles

Estimation of the Value of Forest Ecosystem Services in Pudacuo National Park, China

Forest ecosystems play an important role in maintaining the stability of the biosphere and improving the ecological environment. The valuation of forest ecosystem services provides data to support the implementation of forest ecosystem conservation and the development of ecological-compensation standards. We used multiple sources of data, such as remote-sensing and ground data, and we employed the methods of substitute market, shadow project, and contingent valuation. We valued the forest ecosystem services of Pudacuo National Park in Shangri-La, China, which consisted of six functions: soil conservation, forest nutrient retention, water conservation, carbon fixation and oxygen released, forest health care, and atmospheric environmental purification. The results showed that: the value of forest ecological services in Pudacuo National Park was 4.49 × 109 yuan·a−1, with higher values of carbon fixation and oxygen released, water conservation, and forest health care, in the following order: carbon fixation and oxygen released (3.85 × 109 yuan·a−1), water conservation (3.40 × 108 yuan·a−1), forest health care (1.44 × 108 yuan·a−1), soil conservation (1.15 × 108 yuan·a−1), forest nutrient retention (3.29 × 107 yuan·a−1), and atmosphere environmental purification (1.17 × 107 yuan·a−1). In addition, the value of services per stand and unit area is discussed, and the results of the study will inform the government’s ecological-compensation criteria in high-quality environmental areas

Estimation of the Value of Forest Ecosystem Services in Pudacuo National Park, China

Forest ecosystems play an important role in maintaining the stability of the biosphere and improving the ecological environment. The valuation of forest ecosystem services provides data to support the implementation of forest ecosystem conservation and the development of ecological-compensation standards. We used multiple sources of data, such as remote-sensing and ground data, and we employed the methods of substitute market, shadow project, and contingent valuation. We valued the forest ecosystem services of Pudacuo National Park in Shangri-La, China, which consisted of six functions: soil conservation, forest nutrient retention, water conservation, carbon fixation and oxygen released, forest health care, and atmospheric environmental purification. The results showed that: the value of forest ecological services in Pudacuo National Park was 4.49 × 109 yuan·a−1, with higher values of carbon fixation and oxygen released, water conservation, and forest health care, in the following order: carbon fixation and oxygen released (3.85 × 109 yuan·a−1), water conservation (3.40 × 108 yuan·a−1), forest health care (1.44 × 108 yuan·a−1), soil conservation (1.15 × 108 yuan·a−1), forest nutrient retention (3.29 × 107 yuan·a−1), and atmosphere environmental purification (1.17 × 107 yuan·a−1). In addition, the value of services per stand and unit area is discussed, and the results of the study will inform the government’s ecological-compensation criteria in high-quality environmental areas

A Novel Long Non‐Coding RNA lnc030 Maintains Breast Cancer Stem Cell Stemness by Stabilizing SQLE mRNA and Increasing Cholesterol Synthesis

Abstract Cancer stem cells (CSCs) are considered the roots of cancer metastasis and recurrence (CSCs), due in part to their self‐renewal and therapy resistance properties. However, the underlying mechanisms for the regulation of CSC stemness are poorly understood. Recently, increasing evidence shows that long non‐coding RNAs (lncRNAs) are critical regulators for cancer cell function in various malignancies including breast cancer, but how lncRNAs regulate the function of breast cancer stem cells (BCSCs) remains to be determined. Herein, using lncRNA/mRNA microarray assays, a novel lncRNA (named lnc030) is identified, which is highly expressed in BCSCs in vitro and in vivo, as a pivotal regulator in maintaining BCSC stemness and promoting tumorigenesis. Mechanistically, lnc030 cooperates with poly(rC) binding protein 2(PCBP2) to stabilize squalene epoxidase (SQLE) mRNA, resulting in an increase of cholesterol synthesis. The increased cholesterol in turn actives PI3K/Akt signaling, which governs BCSC stemness. In summary, these findings demonstrate that a new, lnc030‐based mechanism for regulating cholesterol synthesis and stemness properties of BCSCs. The lnc030‐SQLE‐cholesterol synthesis pathway may serve as an effective therapeutic target for BCSC elimination and breast cancer treatment

Correlation between negative life events and suicide attempts among Yi adolescents with HIV/AIDS in Liangshan Prefecture

Abstract Objective To investigate the incidence of suicide attempts among adolescents with HIV/AIDS in Liangshan Prefecture, Sichuan Province, as well as the correlation between negative life events, sleep, exercise, drug therapy and suicide attempts. Methods A total of 180 Yi adolescents aged 11–19 years with HIV/AIDS in a county of Liangshan Prefecture, Sichuan Province, China, were investigated by census. The main outcome indicators included the incidence of suicide attempts and whether negative life events, sleep, exercise, drug therapy and other factors were related to suicide attempts. Results We found that the incidence rate of suicide attempts among Yi adolescents with HIV/AIDS in Liangshan Prefecture was 13.9%. Negative life events were a risk factor for suicide attempts (OR = 1.047, p < 0.001, 95% CI 1.027–1.067). In the factors of negative life events, adaptation was a risk factor for suicide attempts (OR = 1.203, p = 0.026, 95% CI 1.022–1.416), and academic pressure showed a tendency to be a risk factor for suicide attempts (OR = 1.149, p = 0.077, 95% CI 0.985–1.339). However, the punishment factor, interpersonal stress factor and loss factor had no significant correlation with suicide attempts. There was no significant correlation between sleep, exercise, drug therapy and suicide attempts. Conclusion The proportion of suicide attempts among Yi adolescents with HIV/AIDS in Liangshan Prefecture is high and should be considered. Negative life events are independent risk factors for suicide attempts, and it is necessary to strengthen the screening and early intervention for suicide attempts in HIV/AIDS adolescents with definite negative life events