Applied Sciences — Open Access Journal

Ultrasonic wave carries the information for flowing velocity when it is propagating in flowing fluids. Flowrate can be obtained by measuring the propagation time of ultrasonic wave. The principle of transit-time ultrasonic flowmeters used today was based on that the velocity is uniform along the propagation path of the ultrasonic wave. However, it is well known that the velocity profiles in a pipe are not uniform both in laminar flow and turbulent flow. Emphasis on the effects of velocity profiles across the pipe on the propagation time of ultrasonic wave, theoretical flowrate correction factors considering the real velocity profile were proposed for laminar and turbulent flow to obtain higher accuracy. Experiment data of ultrasonic flowmeter and weighting method are compared to verify the proposed theoretical correction factors. The average relative error of proposed correction factor is determined to be 0.976% for laminar flow and 0.25% for turbulent flow. Full article

As renewable energy penetration in power systems grows, adequate energy policies are needed to support the system’s operations with flexible resources and to adopt more sustainable energies. A peak-biased incentive for energy storage systems (ESS) using the Korean renewable portfolio standard could make power system operations more difficult. For the first time in the research, this study evaluates the effect of imposing a renewable energy certificate incentive in off-peak periods on mitigating wind power fluctuations. We design a coordinated model of a wind farm with an ESS to model the behavior of wind farm operators. Optimization problems are formulated as mixed integer linear programming problems to test the implementation of revenue models under Korean policy. These models are designed to consider additional incentives for discharging the ESS during off-peak periods. The effects of imposing the incentives on wind power fluctuations are evaluated using the magnitude of the renewable energy certificate (REC) multiplier. Full article

International policies mainly that are focused on energy-dependence reduction and climate change objectives have been widely proposed by most developed countries over the last years. These actions aim to promote the integration of renewables and the reduction of emissions in all sectors. Among the different sectors, agriculture emerges as a remarkable opportunity to integrate these proposals. Indeed, this sector accounts for 10% of the total greenhouse gas (GHG) emissions in the EU, representing 1.5% of gross domestic product (GDP) in 2016. Within the agriculture sector, current solutions for groundwater pumping purposes are mainly based on diesel technologies, leading to a remarkable fossil fuel dependence and emissions that must be reduced to fulfill both energy and environmental requirements. Relevant actions must be proposed that are focused on sustainable strategies and initiatives. Under this scenario, the integration of photovoltaic (PV) power plants into groundwater pumping installations has recently been considered as a suitable solution. However, this approach requires a more extended analysis, including different risks and impacts related to sustainability from the economic and energy points of view, and by considering other relevant aspects such as environmental consequences. In addition, PV solar power systems connected to the grid for groundwater pumping purposes provide a relevant opportunity to optimize the power supplied by these installations in terms of self-consumption and net-metering advantages. Actually, the excess PV power might be injected to the grid, with potential profits and benefits for the agriculture sector. Under this scenario, the present paper gives a multidimensional analysis of PV solar power systems connected to the grid for groundwater pumping solutions, including net-metering conditions and benefit estimations that are focused on a Spanish case study. Extensive results based on a real aquifer (Aquifer 23) located in Castilla La Mancha (Spain) are included and discussed in detail. Full article

Attention-deficit/hyperactivity disorder (ADHD) is a common neuropsychiatric disorder that impairs social, academic and occupational functioning in children, adolescents and adults. In South Africa, youth prevalence of ADHD is estimated as 10%. It is therefore necessary to further investigate methods that objectively diagnose, treat and manage the disorder. The aim of the study was to develop a novel method that could be used as an aid to provide screening for ADHD. The study comprised of a beta-testing phase that included 30 children (19 non-ADHD and 11 ADHD) between the ages of 5 and 16 years old. The strategy was to use a tablet-based game that gathered real-time user data during game-play. This data was then used to train a linear binary support vector machine (SVM). The objective of the SVM was to differentiate between an ADHD individual versus a non-ADHD individual. A feature set was extracted from the gathered data and sequential forward selection (SFS) was performed to select the most significant features. The test set accuracy of 85.7% and leave-one-out cross-validation (LOOCV) accuracy of 83.5% were achieved. Overall, the classification accuracy of the trained SVM was 86.5%. Finally, the sensitivity of the model was 75% and this was seen as a moderate result. Since the sample size was fairly small, the results of the classifier were only seen as suggestive rather than conclusive. Therefore, the performance of the classifier was indicative that a quantitative tool could indeed be developed to perform screening for ADHD. Full article

In visual inspection of bridges at sites, much attention is given to the density and width of cracks of concrete, but little attention is paid to crack orientation for the diagnosis of bridge performance. In this research, the effect of crack orientation on the remaining fatigue life of reinforced concrete (RC) bridge decks is investigated for crack patterns with a wide range of possible crack orientations. The data assimilation technology of multi-scale simulation and the pseudo-cracking method, which are widely validated for fatigue-lifetime simulation, are utilized in this study. The impact of the crack direction on fatigue life is found to be associated with the coupled flexure-shear mode of failure, and the mechanism to arrest shear cracking by preceding cracks is quantitatively estimated. This mechanism is similar to the stop-hole to prevent fatigue cracks in steel structures, and it enables us to enhance the fatigue life of RC decks. It is demonstrated that the crack orientations that approximate the longitudinal and transverse directions of RC decks are the ones that most extend remaining fatigue life. Finally, the higher risk cracking locations on the bottom surface of RC decks are discussed, presenting information of use to site inspectors. Full article

In recent years, distributed energy storage (DES) has experienced rapid growth and has been widely applied in active distribution networks (ADNs). Owing to the close correlation between the characteristics and the application scenarios, DES modeling needs to be parameterized separately for various application demands. In this paper, a parameterized model for optimal DES planning in ADNs is proposed. The typical scenarios for DES planning are generated by the clustering technique, containing the patterns of load demand, wind turbine output and photovoltaic output. Secondly, an optimal planning model of DES considering parameterized characteristics is established, which is essentially a mixed integer non-linear optimization problem. Then, the model is converted to a mixed-integer second-order cone programming model, which can be solved efficiently by available commercial software. Finally, case studies on the modified IEEE 33-node system and IEEE 123-node system verify the efficiency of the proposed method, and the effects of DES planning are validated by two evaluation indexes. Full article

The boundary element method (BEM) in the context of acoustics or Helmholtz problems is reviewed in this paper. The basis of the BEM is initially developed for Laplace’s equation. The boundary integral equation formulations for the standard interior and exterior acoustic problems are stated and the boundary element methods are derived through collocation. It is shown how interior modal analysis can be carried out via the boundary element method. Further extensions in the BEM in acoustics are also reviewed, including half-space problems and modelling the acoustic field surrounding thin screens. Current research in linking the boundary element method to other methods in order to solve coupled vibro-acoustic and aero-acoustic problems and methods for solving inverse problems via the BEM are surveyed. Applications of the BEM in each area of acoustics are referenced. The computational complexity of the problem is considered and methods for improving its general efficiency are reviewed. The significant maintenance issues of the standard exterior acoustic solution are considered, in particular the weighting parameter in combined formulations such as Burton and Miller’s equation. The commonality of the integral operators across formulations and hence the potential for development of a software library approach is emphasised. Full article

In this study, centrifuge model tests were used to examine the lateral behavior of a
monopile embedded in dry sand through cyclic lateral loading tests. The soil specimens used in the
tests were dry Jumunjin sand with a relative density of 80% and a friction angle of 38°. A static
loading test was performed once, and cyclic loading tests were performed four times using four
magnitudes of cyclic load (30%, 50%, 80%, and 120% of static lateral capacity). The experimental
cyclic p‐y curve was obtained through the tests, and the maximum soil resistance points that were
found for each load were used to find the cyclic p‐y backbone curve for each depth. The two
variables which are needed to define the cyclic p‐y backbone curve, i.e., the initial modulus of
subgrade reaction (k_ini) and ultimate soil resistance (p_u), were suggested as functions of the soil’s
physical properties and the pile. The cyclic p‐y curve of the first cycle and the 100th cycle were
formulated to present the upper limit and lower limit. The suggested cyclic p‐y curve had an
overestimated soil resistance compared with the existing API (1987) method, but the initial modulus
of subgrade reaction was underestimated. Full article

The purpose of this research is to utilize a more advanced test method for investigating the effect of steel corrosion on the flexural characteristics of a reinforced concrete (RC) beam on a microscopic cracking level. Firstly, over-reinforced RC beam specimens were prepared and corroded using an electrical accelerated steel corrosion setup in different ratios. Subsequently, bending and acoustic emission (AE) tests were performed on all the specimens to obtain their ultimate flexural loads, failure modes and AE signals. Furthermore, rise time/peak amplitude (R/A), ringing counts/duration (AF) and improved b (Ib) values, as the statistical parameters of AE signals, were calculated for indicating the transformation of RC specimens’ crack modes and failure modes under the effect of steel corrosion. Finally, the locations of AE events were obtained by localization technology and compared with the locations of concrete cracks (cracks map). The results revealed that the ultimate flexural load decreases with steel corrosion. The crack tends to transform from shear- to tensile-type along with the increase of the steel corrosion ratio. The trend of the Ib-value curve can reflect the formation and development of cracks; and the larger the duration of violent fluctuations in the Ib-value curve is, the larger the ultimate flexural load of the RC beam is. The region where the crack is located can be judged by the position where the relatively dense distribution of the AE events is. Full article

Currently, internal combustion engines (ICEs) are still the main power for transportation. Energy conservation and emission reduction for ICEs have become the driving force of the industrial R&D in recent years. Organic Rankine cycle (ORC) is a feasible technology to recover the waste heat of an ICE so that the energy efficiency can be enhanced apparently. However, there are still many obstacles needed to be overcome for the application of an ORC together with an ICE. When a vehicle is driving, the operation conditions of the ICE vary in a large range. The operation of the ORC needs to be regulated accordingly to achieve maximum efficiency. In this study, the operation characteristics of an ICE-ORC combined system is investigated and the transient performance is analyzed. First, an integrated simulation model of the ICE and the ORC was built in GT-POWER software. A 5 kW single-screw expander was employed for the ORC system. The working characteristics of the ORC system were evaluated under various working conditions of the ICE. The matching principles of the ORC with the ICE were discussed and the optimal operation conditions of the ORC over the entire engine’s working range were obtained. Subsequently, a feedforward control strategy for the ORC system was designed in MATLAB/SIMULINK. Finally, the entire model was simulated under a transient driving cycle of a vehicle. The results indicate that the pump speed and the expander speed are two important parameters and must be adjusted according to the engine’s working condition. The speed of the single-screw expander maintains in the low-speed region and the pump speed is tuned to achieve a high evaporation pressure and a proper superheat degree of the working fluid at the inlet of the expander. Thus, the net power output can be maximized. The designed feedforward control strategy can adjust the working condition of the ORC automatically to match with the working condition of the ICE. The ORC operates intermittently and an impulse power is output under the urban driving conditions. However, the working time of the ORC is increased significantly and the power output is relatively higher under the highway conditions. Full article

Injectable intravaginal hydrogels could deliver drugs systemically without hepatic first pass effect. This paper focuses on the contraceptive function of an injectable temperature-sensitive four-arm star-shaped poly(D,L-lactic-co-glycolic acid)-b-methoxy poly(ethylene glycol) (4sPLGA-mPEG) block copolymer hydrogels as a carrier of three drugs. In vitro controlled release profiles were investigated via HPLC, and it showed that the cumulative release amounts of indomethacin (IMC), gestodene (GSD), and ethinyl estradiol (EE) from copolymer hydrogels could be regulated by adjusting the lactide/glycolide (LA/GA) mol ratio. In addition, in vitro release profiles of IMC, GSD, and EE well corresponded to Higuchi model. The acute toxicity of copolymer hydrogels loaded with different dosage contents multi-drug was evaluated in vivo. As to the high dosage group, the uterus was hydropic at day 1 and ulcerated at day 5, followed with intestinal adhesion. Regarding the middle dosage group, no festering of tissues was observed and, blood coagulum existed in the uterus at different days. For low dosage group, no significant tissue necrosis was found. Finally, the antifertility experiments confirmed that hydrogels loaded with the multi-drug had an excellent contraceptive effect. The above results indicated that injectable copolymer hydrogel as a multi-drug carrier was promising as a novel contraception method. Full article

Ultrasonic (US) neuromodulation has emerged as a promising therapeutic means by delivering focused energy deep into the nervous tissue. Low-intensity ultrasound (US) directly activates and/or inhibits neurons in the central nervous system (CNS). US neuromodulation of the peripheral nervous system (PNS) is less developed and rarely used clinically. The literature on the neuromodulatory effects of US on the PNS is controversial, with some studies documenting enhanced neural activities, some showing suppressed activities, and others reporting mixed effects. US, with different ranges of intensity and strength, is likely to generate distinct physical effects in the stimulated neuronal tissues, which underlies different experimental outcomes in the literature. In this review, we summarize all the major reports that document the effects of US on peripheral nerve endings, axons, and/or somata in the dorsal root ganglion. In particular, we thoroughly discuss the potential impacts of the following key parameters on the study outcomes of PNS neuromodulation by US: frequency, pulse repetition frequency, duty cycle, intensity, metrics for peripheral neural activities, and type of biological preparations used in the studies. Potential mechanisms of peripheral US neuromodulation are summarized to provide a plausible interpretation of the seemly contradictory effects of enhanced and suppressed neural activities of US neuromodulation. Full article

Surface-enhanced Raman scattering (SERS) spectroscopy has attracted a lot of attention over the past 30 years. Due to its extreme sensitivity and label-free detection capability, it has shown great potential in areas such as analytical chemistry, biochemistry, and environmental science. However, the major challenge is to manufacture large-scale highly SERS active substrates with high controllability, good reproducibility, and low cost. In this study, we report a novel method to fabricate uniform silver nanoparticle arrays with tunable particle sizes and interparticle gaps. Using hot embossing and sputtering techniques, we were able to batch produce the silver nanoparticle arrays SERS active substrate with consistent quality and low cost. We showed that the proposed SERS active substrate has good uniformity and high reproducibility. Experimental results show that the SERS enhancement factor is affected by silver nanoparticles size and interparticle gaps. Furthermore, the enhancement factor of the SERS signal obtained from Rhodamine 6G (R6G) probe molecules was as high as 1.12 × 10⁷. Therefore, the developed method is very promising for use in many SERS applications. Full article

Current water color remote sensing algorithms typically do not consider the vertical variations of phytoplankton. Ecolight with a radiative transfer program was used to simulate the underwater light field of vertical inhomogeneous waters based on the optical properties of a eutrophic lake (i.e., Lake Chaohu, China). Results showed that the vertical distribution of chlorophyll-a (Chla(z)) can considerably affect spectrum shape and magnitude of apparent optical properties (AOPs), including subsurface remote sensing reflectance in water (r_rs(λ, z)) and the diffuse attenuation coefficient (K_x(λ, z)). The vertical variations of Chla(z) changed the spectrum shapes of r_rs(λ, z) at the green and red wavelengths with a maximum value at approximately 590 nm, and changed the K_x(λ, z) from blue to red wavelength range with no obvious spectral variation. The difference between r_rs(λ, z) at depth z m and its asymptotic value (Δr_rs(λ, z)) could reach to ~78% in highly stratified waters. Diffuse attenuation coefficient of downwelling plane irradiance (K_d(λ, z)) had larger vertical variations, especially near water surface, in highly stratified waters. Three weighting average functions performed well in less stratified waters, and the weighting average function proposed by Zaneveld et al., (2005) performed best in highly stratified waters. The total contribution of the first three layers to r_rs(λ, 0⁻) was approximately 90%, but the contribution of each layer in the water column to r_rs(λ, 0⁻) varied with wavelength, vertical distribution of Chla(z) profiles, concentration of suspended particulate inorganic matter (SPIM), and colored dissolved organic matter (CDOM). A simple stratified remote sensing reflectance model considering the vertical distribution of phytoplankton was built based on the contribution of each layer to r_rs(λ, 0⁻). Full article

The introduction of Smart Meter Gateways (SMGWs) to buildings and households creates new opportunities and challenges for energy management systems. While SMGWs provide interfaces for accessing recorded information and enable communication to external parties, they also restrict data access to protect the privacy of inhabitants and facility owners. This paper presents an analysis of options for integrating automated (Building) Energy Management Systems (EMSs) into the smart meter architecture based on the technical guidelines for SMGWs by the German Federal Office for Information Security (“Bundesamt für Sicherheit in der Informationstechnik”, BSI). It shows that there are multiple ways for integrating automated EMSs into the German smart metering architecture, although each option comes with its own advantages and restrictions. By providing a detailed discussion of trade-offs, this paper supports EMS designers that will be confronted with differing freedoms and limitations depending on the integration option. Full article

The coupled analysis between a turbine in operating condition and a complex jacket support structure was formulated in this paper for the reliable evaluation of offshore wind turbine structures including pile-soil-structure interactions (PSSIs). Discussions on the theoretical and simulation aspects of the coupled analysis are presented. The dynamic coupled analysis was implemented in X-SEA program and validated with FAST v8 (fatigue, aerodynamics, structures and turbulence) developed by NREL, USA. By replacing the sub-structural module in the FAST with the component of offshore substructure in the X-SEA, the reaction forces and the turbine loads were calculated in each time step and the results from X-SEA were compared with that from FAST. It showed very good agreement with each other. A case study of a NREL 5MW offshore wind turbine on a jacket support structure was performed. Coupled dynamic analyses of offshore wind turbine and support structures with PSSI were carried out. The results showed that in the coupled analysis, the responses of the structure are significantly less than in the uncoupled analysis. The support structure considering PSSI exhibited decreased natural frequencies and more flexible responses compared to the fixed-support structure. The implemented coupled analysis including PSSI was shown to be more accurate and computationally efficient. Full article

This paper describes the construction of a system for the quasi-spectral determination of absorption and scattering parameters of animal tissue phantoms. Several tissue phantoms, including one reference and two modified for examination, were prepared from polydimethylsiloxane (PDMS). The phantoms were measured using a system based on an integrating sphere and the light sources of wavelengths commonly used for the treatment of various diseases in veterinary medicine, including 635 nm (red), 532 nm (green) and 447 nm (blue). The obtained results are consistent with data provided in reference sources and can also be approximated for the entire spectral range of visible radiation (380–780 nm). The developed system is suitable for further measurements of phantoms, which can be adapted to imitate different tissues. Full article

Electric vehicle sharing provides an effective way to improve the traffic situation and relieve environmental pressure. The government subsidy policy and the car-sharing operator’s pricing strategy are the key factors that affect the large-scale application of electric vehicle sharing. To address this issue, a subsidy and pricing model for electric vehicle sharing based on the two-stage Stackelberg game is proposed in this paper according to the current situation in China. First, an electric vehicle sharing operation mode under government participation is constructed. Then, a two-stage Stackelberg game model involving the government, the car-sharing operator and the consumers is proposed to determine the subsidy rates and pricing strategies. The improved particle swarm optimization algorithm is used to obtain the Nash equilibrium of the model. Also, the influence of private car cost and shared travel comfort on subsidy rates and pricing strategies is analyzed. Finally, the simulation of electric vehicle sharing in a town of China is carried out to investigate the performance of the proposed subsidy and price model. The simulation results show that the model rationally formulates subsidy policies and pricing strategies of the electric vehicle sharing to balance the interests of the three participants, mobilizing users’ enthusiasm while guaranteeing the benefits of the government and operator, making the overall benefit optimal. Full article

Walking is classified as the oldest transport mode with the least impact on the environment. It is frequently one of the intermediate transport modes. Generally, while designing exclusive walking transit areas or structures with high human traffic volumes and considering different scenarios, it is advantageous to be able to foresee the congestion conditions and the relative problems. The study of pedestrian trajectories, which are strictly related to the characteristics of the walkers, is necessary and preliminary for the purposes of an in-depth analysis linked to the habits of populations and cultures. Often areas crowded by tourists run, of limited size such as bridges, must be considered in advance for emergencies. This article focuses on an old footbridge of Mostar located in a confined area with an increasing tourist flow. The peculiarity of the bridge lies in the double-flight geometry with elements that generate discontinuity in the trajectory as well as the steps. This analysis was carried out obtaining the traffic data from video cameras and analyzing different scenarios on holidays and weekdays. Also, the possible presence of obstacles on the bridge was taken into account, such as some areas not walkable for temporary work or the presence of obstacles. These scenarios have been calibrated and simulated through the definition of O/D matrices, arcs and nodes (or areas) through the pedestrian simulation tool Viswalk. This comparison is useful for understanding the variation of LOS (Level of Service) during the daily or emergency situations and the results can provide help to local authorities to plan and design an appropriate action plan. Therefore, this research work aims to compare scenarios under critical flow conditions in the order to define preventively possible actions that can guarantee an optimal LOS value during the bridge crossing and the surrounding areas. Full article