Optimal scheduling for refueling multiple autonomous aerial vehicles

The scheduling, for autonomous refueling, of multiple unmanned aerial vehicles (UAVs) is posed as a combinatorial optimization problem. An efficient dynamic programming (DP) algorithm is introduced for finding the optimal initial refueling sequence. The optimal sequence needs to be recalculated when conditions change, such as when UAVs join or leave the queue unexpectedly. We develop a systematic shuffle scheme to reconfigure the UAV sequence using the least amount of shuffle steps. A similarity metric over UAV sequences is introduced to quantify the reconfiguration effort which is treated as an additional cost and is integrated into the DP algorithm. Feasibility and limitations of this novel approach are also discussed.     

Energy saving in wireless sensor networks

With the development of low-cost processor, memory, and radio technologies, it becomes possible to build inexpensive wireless micro-sensor nodes. However, energy is the biggest constraint to wireless sensor capabilities and such constraint combined with a typical deployment of large numbers of sensor nodes have posed many challenges to the design and management of sensor networks. Due to their ad-hoc deployment in hazardous environment, once sensor nodes are deployed in a sensor network, they cannot be easily replaced or recharged. Thus, energy saving acts as one of the hottest topics in wireless sensor networks （WSNs） and hence several energy conservation schemes have been proposed in the literature. In this work, we will make a short survey on the main techniques used for energy conservation in sensor networks. Specifically, we will focus primarily on duty cycling schemes which represent the most suitable technique for energy saving. Moreover, we will also survey in-network processing and network coding techniques which can guarantee a significant amount of energy saving in packet transmission. Finally, we will make a review on some communication protocols proposed for sensor networks.     

Measurement of mechanical and thermal properties of co-sputtered WSi thin film for MEMS applications

In this study, mechanical and thermal properties of the co-sputtered tungsten silicide (WSi) thin film were evaluated to consider the possibility of its use in MEMS applications. WSi film was prepared by co-sputtering and basic micromachining processes, and its mechanical and thermal properties such as Young’s modulus, temperature coefficient of resistance (TCR), strain gauge factor, coefficient of thermal expansion (CTE) and thermal stress were studied. The measurement method was simple and efficient since only one test pattern was used for all measurements. At room temperature, the TCR, gauge factor, CTE and thermal stress were measured to be −670 ppm/°C, 2.8, 32 ppm/°C and 1.76 GPa, respectively. The dependence of these coefficients on temperature was also evaluated experimentally.     

Steady-State Analysis of a Dual-Winding Reluctance Generator With a Multiple-Barrier Rotor

This paper presents the modeling and steady-state performance of a novel dual-winding reluctance generator (DWRG) that uses a multiple-barrier (MB) rotor. A simple mathematical model was developed, and the effects of external parameters (speed, field current, and load) on the steady-state performance were analyzed. Experimental results conducted on a prototype machine were also provided to justify the theoretical approach and performance calculations. The developed model takes into account the magnetic saturation and core loss and enables a quantitative prediction of load characteristics from the no-load test data.     

Structural characterization of coal-hydrogenation products by proton and carbon-13 nuclear magnetic resonance

Heavy oil derived from coal hydrogenation was separated into saturated fractions, neutral aromatic oil, and asphaltene, and these materials were subsequently fractionated according to the magnitude of their respective molecular sizes by gel-permeation chromatography. These GPC subfractions were analysed by proton and carbon-13 n.m.r. spectroscopy and by an additional procedure using gas chromatography for the paraffinic GPC subfractions. ¹³C-n.m.r. spectra for the GPC subfraction of saturated material showed typical long straight-chain paraffin spectral patterns accompanied by iso-and cycloparaffinic carbon signals. The results from gas-chromatographic measurement for the paraffinic GPC subfractions agree fairly well with the trends of average carbon numbers and contents of straight-chain paraffins obtained by varying the fraction numbers, estimated from ¹³C-n.m.r. analyses. The ratios of aromatic carbon to total carbon (f_a) for aromatic oil and asphaltene GPC subfractions obtained directly from ¹³C-n.m.r. spectra are slightly lower than the results from the ¹H-n.m.r. method assuming x = y = 2 in the Brown—Ladner equation. Peak intensities of the respective carbon species in ¹³C-n.m.r. spectra were compared with the peak intensities of correspondingly bonded species obtained from ¹H-n.m.r. measurement. Some inadequacy was recognized in both measurements. It is assumed that there are two reasons for the discrepancy, one of which is the inaccuracy of ¹³C-n.m.r. results owing to the long relaxation times and the effect of Nuclear Overhauser Enhancement, and another is the application of unsuitable values of x and y for calculations from the Brown—Ladner equation. New analytical treatments for ¹³C-n.m.r. results in combination with ¹H-n.m.r. analyses are suggested in this study to avoid these uncertainties in structural analyses. From this procedure, it is believed that the actual contents of aromatic and aliphatic carbon and appropriate values of x and y can be derived.     

Influence of rare earth additives and boron component on electrical conductivity of sodium rare earth borate glasses

Sodium rare earth borate glasses (Na₂O)_35.7(RE₂O₃)_7.2(B₂O₃)_57.1 (RE = Sm, Gd, Dy, Ho, Y, Er, and Yb), were prepared from a mixture of Na₂CO₃, RE₂O₃ and B₂O₃, and their properties as an Na⁺ ionic conductor were investigated. Density increased with increasing atomic weight of RE. Crystallization temperature and crystal melting temperature of the present borate system was lower than that of the previously reported silicate and germanate system. Results of the ¹¹B NMR measurement suggested that half of all boron atoms are coordinated by four oxide ions to give a [BO₄] tetrahedral unit and the others are coordinated by three oxide ions to give a [BO₃] planar triangular unit. The electrical conductivity slightly decreased with increasing the ionic radius of RE³⁺. (Na₂O)_35.7(Y₂O₃)_7.2(B₂O₃)_57.1 glass exhibited the electrical conductivity which is about one order of magnitude lower than those of the previously reported (Na₂O)_35.7(Y₂O₃)_7.2(SiO₂)_57.1 and (Na₂O)_35.7(Y₂O₃)_7.2(GeO₂)_57.1 glasses. It was assumed that this lower electrical conductivity is due to the lower content of Na⁺ ions as conduction species in the former glass, compared with the latter two glasses.     

KCa1.1 K+ Channel Inhibition Overcomes Resistance to Antiandrogens and Doxorubicin in a Human Prostate Cancer LNCaP Spheroid Model

Several types of K⁺ channels play crucial roles in tumorigenicity, stemness, invasiveness, and drug resistance in cancer. Spheroid formation of human prostate cancer (PC) LNCaP cells with ultra-low attachment surface cultureware induced the up-regulation of cancer stem cell markers, such as NANOG, and decreased the protein degradation of the Ca²⁺-activated K⁺ channel K_Ca1.1 by down-regulating the E3 ubiquitin ligase, FBXW7, compared with LNCaP monolayers. Accordingly, K_Ca1.1 activator-induced hyperpolarizing responses were larger in isolated cells from LNCaP spheroids. The pharmacological inhibition of K_Ca1.1 overcame the resistance of LNCaP spheroids to antiandrogens and doxorubicin (DOX). The protein expression of androgen receptors (AR) was significantly decreased by LNCaP spheroid formation and reversed by K_Ca1.1 inhibition. The pharmacological and genetic inhibition of MDM2, which may be related to AR protein degradation in PC stem cells, revealed that MDM2 was responsible for the acquisition of antiandrogen resistance in LNCaP spheroids, which was overcome by K_Ca1.1 inhibition. Furthermore, a member of the multidrug resistance-associated protein subfamily of ABC transporters, MRP5 was responsible for the acquisition of DOX resistance in LNCaP spheroids, which was also overcome by K_Ca1.1 inhibition. Collectively, the present results suggest the potential of K_Ca1.1 in LNCaP spheroids, which mimic PC stem cells, as a therapeutic target for overcoming antiandrogen- and DOX-resistance in PC cells.     

Synthesis of (AB)n-type block copolymers employing surface-active macro-azo initiators

A macro-azo initiator (MAI). prepared by polycondensation of azobiscyanopentanoyl chloride (ACPC) and polyethyleneglycol having average molecular weight of 1000 (PEG1000), was found to show enough surface activity to be usable as an initiator/surfactant (inisurf). Emulsion polymerization of styrene (St) using this MAI as inisurf was carried out and (AB)_n-type poly(PEO-b-PSt) block copolymer (where n represents the block-multiplicity) was obtained. In comparison with solution copolymerization, the emulsion block copolymerization gave PEO-b-PSt with higher molecular weight due to increased block multiplicity. © 1996 John Wiley & Sons, Inc.     

In Situ PD-L1 Expression in Oral Squamous Cell Carcinoma Is Induced by Heterogeneous Mechanisms among Patients

The expression of programmed death ligand-1 (PD-L1) is controlled by complex mechanisms. The elucidation of the molecular mechanisms of PD-L1 expression is important for the exploration of new insights into PD-1 blockade therapy. Detailed mechanisms of the in situ expression of PD-L1 in tissues of oral squamous cell carcinomas (OSCCs) have not yet been clarified. We examined the mechanisms of PD-L1 expression focusing on the phosphorylation of downstream molecules of epidermal growth factor (EGF) and interferon gamma (IFN-γ) signaling in vitro and in vivo by immunoblotting and multi-fluorescence immunohistochemistry (MF-IHC), respectively. The in vitro experiments demonstrated that PD-L1 expression in OSCC cell lines is upregulated by EGF via the EGF receptor (EGFR)/PI3K/AKT pathway, the EGFR/STAT1 pathway, and the EGFR/MEK/ERK pathway, and by IFN-γ via the JAK2/STAT1 pathway. MF-IHC demonstrated that STAT1 and EGFR phosphorylation was frequently shown in PD-L1-positive cases and STAT1 phosphorylation was correlated with lymphocyte infiltration and EGFR phosphorylation. Moreover, the phosphorylation pattern of the related molecules in PD-L1-positive cells differed among the cases investigated. These findings indicate that PD-L1 expression mechanisms differ depending on the tissue environment and suggest that the examination of the tissue environment and molecular alterations of cancer cells affecting PD-L1 expression make it necessary for each patient to choose the appropriate combination drugs for PD-1 blockade cancer treatment.