Desired Period Research Articles

ESTIMATING WATER LEVEL IN THE URMIA LAKE USING SATELLITE DATA: A MACHINE LEARNING APPROACH

Abstract. Lakes play a pivotal role in the development of cities and have major impacts on the ecosystem balancing of the area. Remote sensing techniques and advanced modeling methods make it possible to monitor natural phenomena, such as lakes’ water level. The ecosystem of Urmia Lake is one of the most momentous ecosystems in Iran, which is almost close-ended and has become a global environmental issue in recent years. One of the parameters affecting this lake water level is snowfall, which has a key role in the fluctuations of its water level and water resources management. Hence, the purpose of this paper is the Urmia Lake water level estimation during 2000–2006 using observed water level, snow cover, direct precipitation, and evaporation. For this purpose, Support Vector Regression (SVR), which is the most outstanding kernel method (with various kernel types), has been used. Furthermore, four scenarios are considered with different variables as inputs, and the output of all scenarios is the water level of the lake. The results of training and testing data indicate the substantial impact of snow on retrieving the water level of the Urmia Lake at the desired period, and due to the complexity of the data relationships, the Gaussian kernel generally had better results. On the other hand, Quadratic and Cubic kernels did not work well. The fourth scenario, with RBF kernel has the best results [Training: R2 = 97% and RMSE = 0.09 m, Testing: R2 = 96.97% and RMSE = 0.08 m].

Halbach undulators using right triangular magnets

Undulators and wigglers based on Halbach arrays have been in widespread use since their description in the 1980s, due to the high fields they generate from permanent magnets. The most common implementation of a pure permanent magnet Halbach undulator consists of four magnetic segment widths per undulator period. In typical undulators with periods of order $\ensuremath{\sim}\mathrm{cm}$ it is straightforward to use sufficiently small magnetic segments to achieve the desired undulator period. However, in the context of new microundulators with periods of order $\ensuremath{\sim}\mathrm{mm}$ or shorter, there is a lower bound on the feature sizes achievable by existing fabrication techniques. This motivates the use of modified Halbach arrays comprised of right triangle magnet segments with only two magnet segment widths per undulator period. These configurations are demonstrated to have superior field strengths to up-down arrays with no increase to the undulator period. Additional considerations arising from the broken symmetries in such configurations, such as the presence of previously forbidden harmonic components, are also considered. Such right triangle Halbach arrays may be fabricated using MEMS techniques for use in the next generation of compact light sources.

Event-Triggered Design With Guaranteed Minimum Interevent Times and $\mathcal {L}_p$ Performance

In an event-based scenario, the system decides when to update the actuators based on a real time triggering condition on the measured signals. This condition can be defined in various forms and varies depending on the system properties and design problem. This paper proposes a framework to design the triggering condition while keeping Lp performance within desired limits. Our general framework captures several existing state-based triggering rules as a special case, and can achieve the performance objectives while reducing transmissions. Indeed, this general structure is shown to enlarge the minimum inter-event time by a specified amount, for a desired period of time. Numerical examples suggest that the proposed mechanism effectively enlarges the average sampling time.

Study of particle residence time in a pressurized fluidized bed with in-bed heat exchanger tubes

Anthropogenic climate change is amongst the greatest of challenges to human civilization. A key area that will play a large role in mitigating its effects are clean fossil fuel applications. Clean coal combustion can be achieved with an oxygen-fired pressurized fluidized bed combustor incorporating carbon capture and storage. In relation to pressurized fluidization processes, understanding the influence of pressure on fluidized bed hydrodynamics and, in turn, their effect on parameters including fuel residence time is essential. For the combustor under consideration here, a fraction of the heat exchanger boiler tubes are submerged in the fluidized bed such that the effect of the horizontal tube bundle on the fuel residence time is of great importance. The main focus of the present work was to evaluate the impact of gas velocity, pressure, presence or absence of a horizontal tube bundle and fuel feed rate on the average fuel residence time in a dense gas-solid fluidized bed. Experiments were conducted under cold flow conditions in a pressurized fluidized bed with an inner diameter of 0.15 m. The fluidization material was large glass beads (1.0 mm in diameter) while fuel particles were simulated with smaller glass beads (64 and 83 μm in Sauter mean diameter) that were susceptible to entrainment. Operating pressures and superficial gas velocities were maintained between 101.3 and 1200 kPa and 1.5 and 3.2 Umf, respectively. To simulate continuous fuel injection, experiments were conducted with the fuel surrogate particles being continuously fed to the fluidized bed of large particles over a desired period of time. Downstream, entrained particles were captured to determine the average entrainment rate and average mass of fuel particles inside the fluidized bed at steady state, which yielded the average fuel residence time. The combination of elevated pressure with the tube bundle present was found to have the most influential impact when compared to base conditions of atmospheric pressure and with no tube bundle present. It was found to enhance gas bubble break up and reduce the average gas bubble size substantially. In turn, this increased the average residence time of 83 μm particles by nearly three-fold in comparison to the case of atmospheric pressure with no tube bundle present. The effect of gas velocity on particle residence time was not found to be statistically significant under the range tested. Similarly, the effect of increasing fuel feed rate by 50% had no statistically significant impact.

Poincaré maps design for the stabilization of limit cycles in non-autonomous nonlinear systems via time-piecewise-constant feedback controllers with application to the chaotic Duffing oscillator

Abstract In this paper, a design of Poincare maps and time–piecewise–constant state–feedback control laws for the stabilization of limit cycles in periodically–forced, non–autonomous, nonlinear dynamical systems is achieved. Our methodology is based mainly on the linearization of the nonlinear dynamics around a desired period–m unstable limit cycle. Thus, this strategy permits to construct an explicit mathematical expression of a controlled Poincare map from the structure of several local maps. An expression of the generalized controlled Poincare map is also developed. To make comparisons, we design three different time–piecewise–constant control laws: an mT–piecewise–constant control law, a T–piecewise–constant control law and a T n –piecewise–constant control law. As an illustrative application, we adopt the chaotic Duffing oscillator. By applying the designed piecewise–constant control laws to the Duffing oscillator, the system is stabilized on its desired period–m limit cycle and hence the chaotic motion is controlled.

Consumer intentions to purchase battery electric vehicles in Korea

In Korea, the sales of battery electric vehicles (BEVs) have increased since their introduction to the market in 2010. However, considering the government's plan to introduce BEVs, current BEVs sales in Korea are still below targeted numbers. Among several reasons for this, consumers' intentions and desired time to purchase BEVs are the most important. This study identifies the factors that affect and influence these two reasons. We used survey data containing these two reasons as stated preferences and applied a binary choice model to estimate consumers' intentions to purchase BEVs and an ordered model to estimate the desired period for purchasing BEVs. The study's results show that prior experience driving BEVs and other additional factors—including number of household vehicles, educational level, and perception of government incentives and public parking benefits—have a significant effect on consumers' intentions and desired time to purchase BEVs. Therefore, providing consumers with prior opportunities to drive BEVs is critical for BEVs' full market penetration in Korea.

Reducing our waste size

Reducing our waste size

Electrode material as a decisive factor in electrical resistivity measurement of cement composites

Electrical resistivity measurement is widely used as a method for characterizing different phases of cement composites and evaluating the self-sensing ability of conductive fiber-reinforced cement composites. Since the electrodes play a significant role in measuring the resistivity that enables us to investigate the properties of cement composites, the parameters related to electrodes including material, layout and fixing style must be determined carefully in order to gain a reliable result. In this study, three different materials were used as electrodes to evaluate and compare the electrical behavior of cement mortars. By qualitatively comparing the results in terms of noise fluctuations, resolution and sensitivity, the desired electrode material was determined. Also the polarization and depolarization zones of the specimens containing different fractions of silica fume were investigated so the effect of silica fume on the measured values can be evaluated. Results showed that brass can be a promising candidate as an electrode due to its low current fluctuations and desirable response period, also electrical polarization and depolarization was influenced by the silica fume replacement percentage.

Robust economic model predictive control based on a periodicity constraint

SummaryThis paper proposes robust economic model predictive control based on a periodicity constraint for linear systems subject to unknown‐but‐bounded additive disturbances. In this economic MPC design, a periodic steady‐state trajectory is not required and thus assumed unknown, which precludes the use of enforcing terminal state constraints as in other standard economic formulations. Instead, based on the desired periodicity of system operation, we optimize the economic performance over a set of periodic trajectories that include the current state. To achieve robust constraint satisfaction, we use a tube‐based technique in the economic MPC formulation. The mismatches between the nominal model and the closed‐loop system with perturbations are limited using a local control law. With the proposed robust tube‐based strategy, recursive feasibility is guaranteed. Moreover, under a convexity assumption, the closed‐loop convergence of the closed‐loop system is analyzed, and an optimality certificate is provided to check if the closed‐loop trajectory reaches a neighborhood of the optimal nominal periodic steady trajectory using Karush‐Kuhn‐Tucker optimality conditions. Finally, through numerical examples, we show the effectiveness of the proposed approach.

Films based on the biopolymer poly(3-hydroxybutyrate) as platforms for the controlled release of dexamethasone

Controlled drug delivery aims to achieve an effective drug concentration in the action site for a desired period of time, while minimizing side effects. In this contribution, biodegradable poly(3-hydroxybutyrate) films were evaluated as a reservoir platform for dexamethasone controlled release. These systems were morphological and physicochemically characterized. In vitro release assays were performed for five different percentages of drug in the films and data were fitted by a mathematical model developed and validated by our research group. When the profiles were normalized, a single curve properly fitted all the experimental data. Using this unique curve, the dissolution efficiency (DE), the time to release a given amount of drug (tX%), and the mean dissolution time were calculated. Furthermore, the dissolution rate, the initial dissolution rate (a%) and the intrinsic dissolution rate were determined. The a% mean value was 1.968 × 10−2% released/min, t80% was about 14 days, and the DE was 59.6% at 14 days and 66.5% at 20 days. After 2 days, when approximately 40% of the drug was released, the dissolution rate decreased about 60% respect to the initial value. The poly(3-hydroxybutyrate) platforms behaved as an appropriate system to release and control the dexamethasone delivery, suggesting that they could be an alternative to improve drug therapy.

A Time–Power Series-Based Semi-Analytical Approach for Power System Simulation

Time-domain simulation is the basis of dynamic security assessment for power systems. Traditionally, numerical integration methods are adopted by simulation software to solve nonlinear power system dynamics for any given contingency under a specific operating condition. An alternative simulation approach promising for online applications is to offline derive a semi-analytical solution (SAS) for power system differential equations and then online evaluate the SAS over consecutive time windows regarding the operating condition and contingency until the simulation result over a desired period is obtained. This paper proposes a general semi-analytical approach that derives and evaluates an SAS in the form of a power series in time to approximate the true solution. This paper provides an error-rate upper bound of the SAS for reliable use of adaptive time windows in evaluation of the SAS. To extend the semi-analytical approach for solving general power system differential-algebraic equations, this paper also proposes a dynamic bus method to efficiently link the SAS for dynamic components with the numerical solution of the network algebraic equations. Case studies on the New England 39-bus system and the Polish 2383-bus system test the performance of the proposed approach, compare it with other methods, and show the potentials of the proposed semi-analytical approach for online simulation.

Full state revivals in higher dimensional quantum walks

Full state revivals in a quantum walk can be viewed as returning of the walker to the initial quantum state in a periodic fashion during the propagation of the walk. In this paper we show that for any given number of spatial dimensions, a coin operator can be constructed to generate a quantum walk having full revivals with any desired period. From the point of view of quantum computation and simulations, these coin operators can be useful in implementing quantum walks, which oscillate between any two states with a finite periodicity.

Environmentally Friendly Boron-Based Pyrotechnic Delays: An Additive Manufacturing Approach

Pyrotechnic time delays are reactive systems that burn for a desired period of time at a specified rate and are commonly used in military applications such as grenades and hand-held signals. Typically, they are manufactured by pressing the reactive powder into a metal housing. This rigid design inherently limits configurability, and they have had reliability issues. Additionally, there has been advocacy for environmentally friendly pyrotechnic ignition delays, by removal of barium chromate (BaCrO4). This study has two distinct objectives. First, determine the viability of two possible replacements, strontium molybdate (SrMoO4) and barium molybdate (BaMoO4), for the harmful component, BaCrO4, in the traditional T-10 delay. This includes combustion characteristics such as burning rate, combustion temperature, and gas generation. Furthermore, thermal characteristics are determined through differential scanning calorimetry (DSC), and combustion products are analyzed with X-ray diffraction (XRD). Second, by us...

Male reproductive physiology of Paracentrotus lividus: monthly and seasonal evaluations to study the effects of the environment on gonadal development and sperm cells kinetic

Paracentrotus lividus is a model species for research in different areas, it is also important for modern aquaculture interested in breeding innovative species for greater product diversifications and reduction of the wild stock fishing pressure. This Echinoid was considered a seasonal niche product in the past; nowadays it is highly required on the market for the nutritional characteristics (high protein and low fat) of gonads, the edible part. Our work aims at optimizing farm technics by the study of the habitat impact on P. lividus male reproductive physiology. We correlated environmental variables of the fishing area (temperature, humidity, photoperiod, water temperature, moon phases) to reproductive parameters (morphological gonadal development, sperm cells kinetic). We analyzed data to highlight the relevance, for reproduction, of the length (month or season) of the observations. The significance of this work to the field of aquatic sciences is to drive aquaculture facilities in choosing the desirable period to recover the best spermatozoa with highest total and progressive motility. Moreover setting useful parameters to mimic the best environmental conditions, the highest gonadal development could be reached. This could also promote gametes exchanges between aquaculture facilities in the world taking advantage of the environment dependent gametes maturity.

Bioresorbable Silicon Nanomembranes and Iron Catalyst Nanoparticles for Flexible, Transient Electrochemical Dopamine Monitors.

A strategy of materials synthesis, characteristic evaluations, and manufacturing process for a mechanically elastic, biologically safe silicon-based dopamine detector that is designed to be completely transient, i.e., dissolved in water and/or biofluids, potentially in the brain after a desired period of operation, is introduced. Use of inexpensive, bioresorbable iron (Fe)-based nanoparticles (NPs) is one of the attractive choices for efficient catalytic oxidation of dopamine as an alternative for noble, nontransient platinum (Pt) nanoparticles, based on extensive studies of synthesized materials and catalytic reactions. Arrays of transient dopamine sensors validate electrochemical functionality to determine physiological levels of dopamine and to selectively sense dopamine in a variety of neurotransmitters, illuminating feasibilities for a higher level of soft, transient electronic implants integrated with other components of overall system.

Knowledge and attitudes about HIV-AIDS in a pregnant women population in Southwestern Madagascar

This work reports the knowledge and attitudes of a sample of pregnant women from Tulear, Madagascar. While 91.3% of the 396 women recruited reported experiencing HIV-AIDS, 62.1% could express knowledge of at least one appropriate mode of protection against the disease. Radio and other mass media represented the most frequent source of information. 31.3% of women strongly discriminated against patients with HIV/AIDS. There was no significant relationship between knowledge of the means of protection against HIV-AIDS and the different biomarkers of STIs obtained. 81.7% of women were condom users, but only 5.4% used it as a method of contraception outside the desired period of pregnancy. Low-educated women from the South West appeared to be particularly at risk of not knowing about HIV, and would require the implementation of appropriate information programs.

Critical Review on Standard Operative Procedure of Yapana Basti Karma

Panchakarma therapy is one of the vital branch of Ayurveda, which deals mainly with purification of the provoked Doshas from the body. Basti Chikitsa is regarded as the prime treatment modality among the Panchakarma. It is having not only curative action but also preventive and promotive actions. It is considered as best treatment for Vata Dosha. Yapana Basti is a subtype of Asthapana Basti, which is having the property to support life and promote longevity and widely used in various disorders. Rajayapana Basti is superior amongst all the Yapana Bastis described by Acharya Charaka as it is the king of Yapana. This Rasayana Yapana Basti performs dual function of both Anuvasana and Niruha; hence this is Srotoshodhaka and Brimhana at the sametime. That’s why there is no need to administer separate Anuvasana while giving Yapana Basti. There is an urgent need of standardizing the classical Panchakarma procedures in consideration of the need of today. The dosage schedule, exact procedures, medicaments, effects, and side effects are to be standardized so that uniform procedure of practice should be followed all over nation. Standardization is the need of hour for physicians, to prevent Atiyoga (over activity), Ayoga (less or no activity) and to get adequate effects in a systematic and sophisticated manner within desired time period.

Synchronization of Discretely Coupled Harmonic Oscillators Using Sampled Position States Only

This technical note studies the synchronization of discretely coupled harmonic oscillators by using an impulsive control strategy. In the absence of velocity measurements, a distributed protocol for the coupled harmonic oscillators is proposed under the assumption that each oscillator can only obtain the information of its position relative to its neighbors at a series of discrete time moments. Necessary and sufficient conditions are established for the synchronization of the networked system with and without an active leader over an undirected communication topology. The desirable sampling period is analytically found to be dependent on the network topology and position gain. A simple iterative method is developed to calculate the range in which the sampling period falls. Finally, numerical simulations are performed to show the effectiveness of the proposed protocols.

Real-time control of stormwater detention basins as an adaptation measure in mid-size cities

ABSTRACTThe performance of predictive real-time control (RTC) of outflow from a detention basin, integrating rainfall forecasts in the definition of the control rules, was assessed in terms of peak flow reduction in the receiving water body, improvement of the level of service of the stormwater network downstream and qualitative treatment of runoff. Evaluations were performed using the PCWMM software with rainfall data for a continuous 6-month period and four individual events, in a future climate. As compared to the situation with static control, peak flows at the outfall were reduced by an average of 46% with predictive RTC, and the downstream collector was used up to 22% less during rainfalls. Also, the detention time reached the desired period of 36 h for water quality control, for most of the simulated rainfall events. This demonstrates the usefulness of RTC as an adaption measure to climate change in existing urban areas.

A Novel Methodology for Multiple-Year Regulation of Reservoir Active Storage Capacity

Reservoir design entails the determination of the required storage capacity over multiple years of low flow conditions to ensure the coverage of multiple-purpose water demands. Dam operation depends on many factors that may result in the decrease of required safe yields, leading to inadequate outflow supplies in the design period. This study addresses two issues: (a) the computation of reservoir active storage capacity performed with the aid of the new concept of a zero-height dam, a procedure easy to interpret physically and implement computationally; and (b) the generation of appropriate inflow data, provided that a substantial record of monthly inflows is available. The treatment of the inflow data for the generation of inflow sequences for any desired regulation period is performed by two original methods (First and Second), which are entirely different from other available methods and allow for the selection of a reservoir capacity with the desired level of exceedance probability. The two methods proposed give practically the same results. However, the Second Method, which generates inflow data consisting of hydrologic years with inflow values for each month randomly selected from the observed values for that month, is superior in terms of the ease with which inflow sequences are generated. Also, due to the large size of the random sample that can be generated, the exceedance probability curves are very smooth and allow for the easy selection of reservoir storage capacity with any level of desired exceedance probability. The proposed methodology may be useful for consultants and reservoir managers.