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The novel two-dimensional hexagonal boron nitride (h-BN) decorated nickel oxide (NiO) heterojunction was successfully synthesized by a facile solvothermal precipitation method combining with heat treatment. SEM and TEM analysis were used to corroborate the average size (~8 nm) and overall distribution of superfine NiO nanoparticles on h-BN. XRD, FT-IR and XPS characterization confirmed the configuration of highly crystallinity and p-n heterojunction as well as the presence of surface oxygen vacancy defects. Gas sensing test results revealed that the decoration of h-BN could significantly enhanced triethylamine (TEA) sensing property of NiO. The main contribution of such remarkable results lies in NiO nanoparticles that are close to Debye length scale were embedded on vacancy defects of functionalized h-BN nanosheets, which can optimize sensitivity and selectivity by taming two-dimensional (2D) interfacial electronic effects that strongly affect nonmetal-support interaction between grain boundaries. Meanwhile, the formation of p-n Schottky nanoscale heterojunction between NiO and h-BN can significantly enlarge resistance variation and efficiently promoted the adsorbed triethylamine molecules to oxidize into NO2, H2O, and CO2. Our work highlights the important role of coupling functionalized h-BN in gas sensors, which can also provide a valuable avenue in boosting the sensing performance.

In this work, graphitic carbon nitride nanosheets decorated like nickel oxide microspheres (NiO/g-C 3 N 4 , Ni/CN) were successfully synthesised by a simple hydrothermal method. The morphologies of the as-prepared samples were analysed by scanning electron microscopy and the diameter of the microspheres was found to be about 2.5 μm. At an optimum working temperature of 240°C, the response to 500 ppm CO is 2.729 for the Ni/CN-10 (10 wt% g-C 3 N 4 modified NiO) sensor, which is much higher than those of the NiO sensor (1.408). Besides the higher response, the Ni/CN sensors also showed good repeatability and stability for CO detection. Excellent gas sensitivity properties can be attributed to the p-n heterojunction formed at the interface, which can provide more potential active sites for surface reactions. In addition, the sensitisation of g-C 3 N 4 also plays an important role in the improvement of CO-sensing performance.

Multiple piezoelectric power sources are used for extending the bandwidth or the multi-direction operation capability of the vibration harvesters. Typical rectifier configurations including parallel or series connection before a shared rectifier or one rectifier per source are usually used for regulating the multiple sources. The problem of charge cancelation arises for the shared rectifier configuration while diodes are too many for the configuration of one rectifier per source. In this article, improved rectifier design is proposed for multiple sources by introducing a common ground branch. The improved scalable rectifier design is capable of unifying more than one sources of different voltage polarity to power the load without charge cancelation, thus promising better performance than the aforementioned configurations. The power enhancement is verified through simulations and experiments with a maximum boost of 91.9% and the effective bandwidth is increased by 23.3% at least. In particular, the design has the advantage of cost saving by reducing the diodes to almost the half in comparison with the configuration of one rectifier per source.

Through a simple performance dynamic modulus test (SPT), standard rutting test, Hamburg rutting test, French rutting test and asphalt pavement analyzer rutting test, the rutting resistance of asphalt mixtures in the middle and lower courses of three semi-rigid base asphalt pavement of Beijing full-scale test track road in China was evaluated. The test results show that the rutting resistance of asphalt mixtures of the middle and lower courses can be greatly improved by using low-grade asphalt, especially 30# asphalt. The rutting resistance of SBS modified asphalt mixtures is also better. The SPT dynamic modulus test can indirectly characterize the rutting performance of the asphalt mixture. The rutting test results of a laser road detection vehicle and 3 m ruler show that the asphalt grade has a significant impact on the rutting performance of semi-rigid base asphalt pavement. Compared with 70# asphalt used in the middle and lower courses, the rutting resistance of the pavement structure can be improved by more than 20%. The result also show that the APA rutting test results can closely characterize the full-scale test track results, which is an optimal test method for evaluating the rutting performance of semi-rigid base asphalt pavement. The research results can provide a theoretical basis and reference for the rational design and rutting evaluation of semi-rigid base asphalt pavement.

The search for anode materials with high performance and low cost for lithium-ion batteries (LIBs) remains challenging. Herein, Earth-abundant and acid-resistant jarosite ultrathin KFe3(SO4)2(OH)6@rGO (KFN@rGO) nanosheets were fabricated via a facile and scalable hydrothermal route without any surfactant. When serving as an anode material for LIBs, KFN@rGO delivers excellent lithium storage performances, including high reversible capacity (913 mA h g−1 at 20 mA g−1) and robust cycling life (545 mA h g−1 at the end of 1000 cycles at 500 mA g−1). Moreover, the pseudocapacitive contribution is as high as 62.7% at 1 mV s−1 as revealed by cyclic voltammetry. The robust cycling stability can be attributed to the hybrid structure of ultrathin KFe3(SO4)2(OH)6 nanosheets and flexible rGO which not only enhances the conductivity and structural integrity, but also induces the pseudocapacitive effect during the cycles. This work may provide an effective route to improve the electrochemical performances of other jarosite minerals through the introduction of the pseudocapacitive contribution.

Efforts have been recently devoted to improving the performance of the piezoelectric energy harvesters (PEHs) from the electrical side, in both power harvesting efficiency and operating frequency bandwidth. The frequency-tuning concept for synchronous electric charge extraction (SECE) circuit is a feasible solution by simultaneously adjusting the energy extraction phase and the voltage reversal ratio, especially for highly coupled PEHs. However, in-depth analysis on the influence of the two tuning parameters on the electromechanical system is still not provided. In this paper, the frequency-tuning strategy has been introduced to the optimized SECE (OSECE) circuit in which the two-parameters tuning strategy can be realized more conveniently in comparison with the SECE circuit due to the common ground. Detailed analysis on the frequency-tuning OSECE technique reveals how the energy extraction phase and the voltage reversal ratio affect the system characteristics respectively. Moreover, special consideration is focused on the circuit quality factor which is shown to be a critical factor for determining the tuning parameters. Comparative studies have been performed between the proposed frequency-tuning OSECE (FT-OSECE), the frequency-tuning SECE (FT-SECE), the frequency tunable SECE (only varying the extraction ratio), phase-shift SECE (only varying the extraction phase), conventional SECE and OSECE. Good agreement between the theoretical and experimental results confirms the accuracy of the proposed model and FT-OSECE shows similar performance to FT-SECE with the aforementioned advantages of circuit implementations.

The critical chain scheduling and buffer management (CC/BM) methodology has proven to be a favorable approach to schedule resource-constrained projects and to offer a valuable control tool for monitoring projects under uncertainty. The previous studies on CC/BM seem to have neglected the cost performance, which might render its wider applications to the modern economic activities that are mostly performed in a project way. This paper presents an improved CC/BM framework that allows additional resource allocation/reallocation to bring forward activity starting times based on cost and schedule stability criteria. In the planning phase, the decision is made concerning the regular resource availability period in order to minimize the expected resource costs. In the execution phase, a scheduled order repair method for rescheduling along with two reactive resource allocation procedures as the corrective action whenever delays are beyond a certain buffer threshold are presented and examined in order to exhibit a comprehensive project schedule/cost control system that is adaptive to the CC/BM management logic. Finally, our computational experiment demonstrates the benefits of the proposed reactive methods under different cost or availability parameters.

As a representative variant of the project scheduling problems, the discrete time/resource trade-off problem (DTRTP) is very important in both theory and practice. This paper investigates the stoch...

Dedicated units are generally needed for operating the switches in synchronous extraction circuits which are considered to be effective in enhancing the power of piezoelectric generators. This paper presents a novel design of self-adaptive mechanical switch using viscous materials. It can trace the displacement peaks and perform the switching operations synchronously with higher performance, less electronic components and lower voltage threshold. A parameter study shows that the relaxing time of the viscous material has different effects in the case of harmonic and noise excitations with varied optimization goals.

In previous research (Tian and Demeulemeester 2010), we have shown that in realistic situations railway scheduling improves both the stability and the expected project length over roadrunner scheduling. In this paper, we introduce the concept of resource flow networks in this analysis and determine what the impact of combining roadrunner or railway scheduling with priority lists or resource flow networks is on the average project length, the standard deviation of the project length, the timely project completion probability and the stability cost. Extensive computational results will be presented on both small and larger projects and a statistical analysis will be conducted by using SAS PROC GLM, indicating that in smaller projects the optimal combination strongly depends on the performance indicator of interest, while in larger projects a combination of roadrunner scheduling with a resource flow network seems optimal.

Critical chain project management, proposed by Goldratt, has proven to be a good methodology to schedule the resource-constrained projects in the past decades. Buffer management is one of the main features of the CCPM. There are a lot of researches about the buffer size methods, however not so much on the rescheduling after inserting the buffer. AS we know, there might be resource or precedence conflict after inserting the feeding buffer. It is the objective of this paper to introduce how to reschedule after inserting the buffer in the project. We propose two reschedule methodologies-local repaired reschedule and global reschedule to solve the resource and precedence contentions and some computation results are provided to compare those methodologies.

The Critical Chain Scheduling and Buffer Management (CC/BM) methodology, proposed by Goldratt (1997), introduced the concepts of feeding buffers, project buffers and resource buffers as well as the roadrunner mentality. This last concept, in which activities are started as soon as possible, was introduced in order to speed up projects by taking advantage of predecessors finishing early. Later on, the railway scheduling concept of never starting activities earlier than planned was introduced as a way to increase the stability of the project, typically at the cost of an increase in the expected project makespan. In this paper, we will indicate a realistic situation in which railway scheduling improves both the stability and the expected project makespan over roadrunner scheduling.

In previous research (Tian & Demeulemeester, 2010), we have shown that in realistic situations railway scheduling improves both the stability and the expected project length over roadrunner scheduling. In this paper, we introduce the concept of resource flow networks in this analysis and determine what the impact is of the resulting combinations on the average project length, the standard deviation of the project length, the timely project completion probability and the stability cost. Extensive computational results will be presented on both small and larger projects and statistic analysis will be conducted by using SAS PROC GLM.