Porcellio scaber algorithm (PSA) for solving constrained optimization problems

In this paper, we extend a bio-inspired algorithm called the porcellio scaber algorithm (PSA) to solve constrained optimization problems, including a constrained mixed discrete-continuous nonlinear optimization problem. Our extensive experiment results based on benchmark optimization problems show that the PSA has a better performance than many existing methods or algorithms. The results indicate that the PSA is a promising algorithm for constrained optimization.Comment: 6 pages, 1 figur

A dual-grating InGaAsP/InP DFB laser integrated with an SOA for THz generation

We report a dual-mode semiconductor laser that has two gratings with different periods below and above the active layer. A semiconductor optical amplifier (SOA), which is integrated with the dual-mode laser, plays an important role in balancing the optical power and reducing the linewidths of the emission modes. A stable two mode emission with the 13.92-nm spacing can be obtained over a wide range of distributed feedback and SOA injection currents. Compared with other types of dual-mode lasers, our device has the advantages of simple structure, compact size, and low fabrication cost

Tunability and performance enhancement for planar microwave filters

Radio-frequency (RF) spectrum is exploited as a valuable resource for wireless applications such as mobile and satellite communications. As a result, communication systems including satellite communication and emerging 5G are trending to have frequency-agility to adapt to highly complex RF environments. However, due to the nature of materials and components, electrically-tunable planar filters, which play essential roles in frequency agile RF systems, have their disadvantages of low-order, high-loss, and poor selectivity. This has limited the overall performances of the frequency agile RF systems. In the light of this scenario, the objective of this thesis is to develop efficient performance-enhancement techniques, including the lossy technique, and the active technique, into the high-selective tunable planar filters to boost the performances of tunable RF systems. First of all, an electrically reconfigurable microstrip dual-mode filter is demonstrated with nonuniform-quality-factor lossy technique. The 4-pole bandpass filter exhibits a continuously bandwidth tuning and centre frequency tuning capability. By making use of the doubly tuned resonant property of the dual-mode microstrip open-loop resonator, passband flatness can be improved by simply loading resistors on the even-odd mode symmetrical plane of resonators. Moreover, two intrinsic transmission zeros are in upper and lower stopbands enhancing the filter selectivity. The coupling matrix synthesis is introduced to describe the nonuniform-quality-factor distribution in a filter network. The experiment of this type of four-pole tunable lossy filter has presented a good agreement with the simulation. Then, the thesis reports a novel 5-pole lossy bandpass filter with the bandwidth tunability. In order to improve the filter selectivity, we choose a hybrid filter structure consist of hairpin resonators and dual behaviour resonators to produce two adjustable transmission zeros for high selective responses. A novel lossy technique named centre-loaded resistive cross-coupling is developed to efficiently reduce the insertion-loss variation of the tuned passband. The fabricated filter demonstrates an insertion loss variation of less than 1 dB for all bandwidth states. To compensate the loss within the varactor-tuned narrowband filter, a tunable 2-pole active filter is presented with a constant absolute bandwidth. The negative resistance generated from active circuits successfully cancels the loss within the varactor-loaded resonators resulting in high quality-factor resonator filter responses. With the transistor small-signal model, the value of the negative resistance of the active circuit can be predicted by network analysis. Experiments were carried out to validate the design

Graph-based SLAM-Aware Exploration with Prior Topo-Metric Information

Autonomous exploration requires the robot to explore an unknown environment while constructing an accurate map with the SLAM (Simultaneous Localization and Mapping) techniques. Without prior information, the exploratory performance is usually conservative due to the limited planning horizon. This paper exploits a prior topo-metric graph of the environment to benefit both the exploration efficiency and the pose graph accuracy in SLAM. Based on recent advancements in relating pose graph reliability with graph topology, we are able to formulate both objectives into a SLAM-aware path planning problem over the prior graph, which finds a fast exploration path with informative loop closures that globally stabilize the pose graph. Furthermore, we derive theoretical thresholds to speed up the greedy algorithm to the problem, which significantly prune non-optimal loop closures in iterations. The proposed planner is incorporated into a hierarchical exploration framework, with flexible features including path replanning and online prior map update that adds additional information to the prior graph. Extensive experiments indicate that our method has comparable exploration efficiency to others while consistently maintaining higher mapping accuracy in various environments. Our implementations will be open-source on GitHub.Comment: 8 pages, 6 figure

Maximizing the Probability of Arriving on Time: A Practical Q-Learning Method

The stochastic shortest path problem is of crucial importance for the development of sustainable transportation systems. Existing methods based on the probability tail model seek for the path that maximizes the probability of arriving at the destination before a deadline. However, they suffer from low accuracy and/or high computational cost. We design a novel Q-learning method where the converged Q-values have the practical meaning as the actual probabilities of arriving on time so as to improve accuracy. By further adopting dynamic neural networks to learn the value function, our method can scale well to large road networks with arbitrary deadlines. Experimental results on real road networks demonstrate the significant advantages of our method over other counterparts

Evaluation of high mobility group box 1 protein as a presurgical diagnostic marker reflecting the severity of acute appendicitis.

RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.OBJECTIVES: To validate the role of high mobility group box-1(HMGB1) in diagnosis of acute appendicitis (AA) with different pathological severity. METHODS: According to the pathologically diagnosis, 150 patients underwent appendectomies between Jan. 2007 and Dec, 2010 were divided into acute simple, acute suppurative and acute gangrenous appendicitis as group 1, 2 and 3, respectively. Each patient group contains 50 sex and age matched cases to make comparison with 50 healthy volunteers. The mRNA and protein expression levels of serum HMGB1 were determined by real-time quantitative PCR and enzyme linked immunosorbent assay (ELISA). Serum High-sensitivity C-reactive protein (hs-CRP) levels were determined by rate nephelometric immunoassay. RESULTS: In comparison with health volunteers, relative HMGB1 mRNA levels in group 1, 2 and 3 were significantly increased 3.05 ± 0.51,8.33 ± 0.75 and 13.74 ± 1.09 folds, reflecting a tendency of augmented severity. In accordance, serum protein levels of HMGB1 were 10.97 ± 1.64, 14.42 ± 1.56 and 18.08 ± 2.41 ng/ml in 3 patient groups, which are significantly higher than that of healthy volunteers' 5.47 ± 0.73 ng/ml. hs-CRP levels were 12.85 ± 3.41, 21.04 ± 1.98 and 31.07 ± 5.46 ng/ml in 3 patients groups compared with 2.06 ± 0.77 ng/ml in controls. The concentrations of HMGB1 and hs-CRP were both positively correlated with disease severity. CONCLUSION: Serum HMGB1 constitutes as a valuable marker in diagnosis of AA. Positively correlated with hs-CRP level, mRNA and protein expression of HMGB1 to a certain extent reflected the severity of AA

Efficient Neural Neighborhood Search for Pickup and Delivery Problems

We present an efficient Neural Neighborhood Search (N2S) approach for pickup and delivery problems (PDPs). In specific, we design a powerful Synthesis Attention that allows the vanilla self-attention to synthesize various types of features regarding a route solution. We also exploit two customized decoders that automatically learn to perform removal and reinsertion of a pickup-delivery node pair to tackle the precedence constraint. Additionally, a diversity enhancement scheme is leveraged to further ameliorate the performance. Our N2S is generic, and extensive experiments on two canonical PDP variants show that it can produce state-of-the-art results among existing neural methods. Moreover, it even outstrips the well-known LKH3 solver on the more constrained PDP variant. Our implementation for N2S is available online.Comment: Accepted at IJCAI 2022 (short oral