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One of the greatest challenges for the sustainability of soybean production in Brazil is the control of Asian soybean rust (ASR). This study aimed to assess the climate risk of ASR occurrence throughout the period recommended for sowing in four locations of Rio Grande do Sul, considering different soybean relative maturity groups and the phases of the El Nino–Southern Oscillation phenomenon. The soybean development cycle and the climate favorability for ASR occurrence were simulated for the recommended sowing dates in the period from 1961 to 2020 in four locations of Rio Grande do Sul. Early cultivars, sown at the beginning of the period recommended by Agricultural Zoning of Climate Risk, usually exhibit less favorable climate conditions for ASR occurrence and less interannual variability in their cycle. The effect of the El Nino/Southern Oscillation phenomenon varies across the studied locations, with the prevalence of more favorable conditions for ASR occurrence during El Nino years. However, neutral years show greater interannual variability for the risk of ASR occurrence.

The purpose of the present paper is to investigate the flow and heat transfer of a double fractional Maxwell fluid with a second order slip model. The fractional governing equations are solved numerically by using the finite difference method. By comparing the analytical solutions of special boundary conditions, the validity of the present numerical method is examined. The effects of the two slip parameters and the fractional parameters on the velocity and temperature distribution are presented graphically and discussed. The results reveal that the fractional Maxwell fluid exhibits a stronger viscosity or elasticity for different fractional parameters, and the oscillation phenomenon will gradually decrease as expected with an increase in slip parameters.

To clarify the effect and mechanism of oxygen supply, particle size, and dust concentration on the flame propagation behaviours and explosion characteristics of cornstarch dust cloud, a 3D numerical simulation for simulating the explosion process of cornstarch dust cloud were conducted and verified with experimental data using a 20-L sphere. Next, flame behaviours and explosion parameters under different conditions were investigated using numerical calculation and experimental observation. Results revealed that: flame propagation during the whole explosion process can be divided into four various stages according to the CFD simulation. Temperature fluctuation, dust agglomeration, and three different zones can be distinguished from the flame configuration. Oxygen supply, particle size, and dust concentration pose different impact trends to the initial flame behaviours and explosion parameters. The flame length varied linearly over time while oscillation phenomenon can be found in flame velocity at both the horizontal and vertical directions.

The neural baroreflex, which regulates mean arterial pressure (MAP) via the action of the brain, consists of baroreceptors which measure MAP, and actuators that can produce a change in MAP, such as the heart and parts of the peripheral resistance containing innervated smooth muscle. The brain is the controlling unit, maintaining an appropriate MAP in spite of various disturbances. Under certain circumstances, including haemorrhage and other states of distress, the gain of the neural baroreflex can change, causing low frequency (LF) oscillations (sometimes termed Mayer waves) in blood pressure (BP). Though their purpose is unclear, the origins of these LF oscillations has previously been explained via a nonlinear feedback model, though focusing on the peripheral resistance as an MAP actuator only. The present paper now includes analytical and simulation results explaining the LF oscillation phenomenon for the full neural baroreflex, containing both peripheral resistance (PR) and cardiac branches. However, the main contribution of the paper is to examine the effect of blood pulsatility, or a lack of pulsatility, on the neural baroreflex, and how it's effect can manifest in the presence of LF oscillations. This may have importance in cases where pulsatility is reduced (for example where left-ventricular assist devices are present), or completely absent (for example in turbine-based artificial hearts).

A multi-power reaching law of sliding mode control is applied to aero-engine control, for which the tracking controller is designed based on sliding mode control. An improved multi-power reaching law of sliding mode control is proposed in this paper, which aims at reducing high-frequency oscillation phenomenon appeared in multi-power tracking control process of aero-engine. The proposed reaching law is used in a simulation of an aero-engine control system, whose results show that the proposed reaching law is applicable for tracking control of aero-engine. Not only does the proposed reaching law has these advantages that are fast response speed and strong robustness but also it can inhibit high-frequency oscillation phenomenon. The proposed reaching law is also used in aero-engine controller experiment. The improved multiple reaching law of sliding mode is suitable for tracking control for aero-engine.

Chemical CD oscillation and chemical resonance phenomena appear in a competitive chemical reaction system involving amplification. A pseudoenantiomeric mixture of an aminomethylenehelicene (P)-tetramer and an (M)-hexamer in toluene forms three states, namely hetero-double-helix B, hetero-double-helix C, and dissociated random-coil 2A. When the temperature of the solution is oscillated between −5 and 38 °C at a rate of 2 K min−1, Δe reaches maxima twice during a single temperature oscillation, which is called a chemical CD oscillation phenomenon. The phenomenon arises from the sharp competition between the two self-catalytic 2A + C-to-2C and 2A + B-to-2B reactions. In addition, the chemical CD oscillation appears, when temperature oscillation occurs at a rate of 2 K min−1, and higher and lower rates provide a single maximum, a process referred to as the chemical resonance phenomenon. The changes in concentration induced by temperature oscillation repeatedly crossed equilibrium.

Owing to the fast control response and distinct characteristics of the voltage source converter (VSC), various types of oscillation incidents related to the VSC-HVDC systems have been observed around the world. However, the causes of such oscillations are complex due to the interactions among the components of the transmission system and the various control methods of the converter station, and yet not systematically comprehended and summarised. Therefore, this study reviews several typical VSC-HVDC oscillation incidents and focuses on the root causes of the oscillation phenomenon. The analysis indicates that the oscillations in the VSC-HVDC system can occur either in subsynchronous frequency or in high-frequency range, up to 1.2 kHz. The modelling methods, including the conventional detailed model, equivalent detailed model, and average equivalent model, are also affecting the accuracy of describing the oscillations. The control methods, including adding active control scheme, passive filter at oscillation frequency, and temporary power plant disconnections, are also discussed. The advantages and drawbacks of these modelling methods, analysis methods, and control methods are summarised based on the various system conditions. In the end, the future research perspectives and key challenges are provided for further research references.

Oscillation is a day-to-day phenomenon. When you take little children into the park and they go on the swing, the swing goes back and forth and that is called oscillation. The swing oscillates because of the force of gravity pulling it down when it stops at its highest point. Without the force of gravity, the swing, once pushed, instead of oscillating back and forth would just go around the pole in big circles with the strings remaining rigid. That would not be much fun since the child sitting on the swing would be upside down at the top, but would not come down, since there would be no gravitational force to pull him or her down. There always has to be some force for the oscillation to take place. Thus, just like gravitational force makes the swing go back and forth and makes it oscillate, it follows that any oscillation phenomenon is an indication of the existence of a force of some kind.

The need to validate the quality of evapotranspiration estimates is essential for this parameter which has extended its use. For this, it is necessary to evaluate both new remote sensing products that expand the areas of estimated evapotranspiration and empirical equations that provide estimates with different data requirements. In order to examine this problem, the present study compared the estimates of evapotranspiration obtained by remote sensing of the MOD16A2 product and seven empirical equations with the estimates obtained through the FAO-56 reference method, with data obtained from six meteorological stations in the State of Rio de Janeiro, Brazil. Data cover the period from 2007 to 2013, which contains different phases of the El Nino–Southern Oscillation phenomenon. The methods proposed by Valiantzas were those that obtained the best performances when compared with FAO-56 with R2 over 90%. The non-parametric analysis of Mann-Kendall for the six seasons was mostly not significant; only the station of Resende showed a tendency of significant growth during the El Nino episode (Z = 0.283 and p value = 0.050). The mangrove and forest classes were the ones that obtained the highest averages (3.75 mm d−1 and 3.62 mm d−1), where the gradient of evapotranspiration can be observed in the South-Northeast portions. The MOD16A2 orbital product was inferior to the methods that used surface meteorological station data.

First results on the energy spectrum and flux of reactor antineutrinos as a function of the distance L from the reactor core, measured in the Neutrino-4 experiment for 6 < L < 12 m, are presented. The flux L‑dependence fits to the 1/L2 form with a statistical significance of ~10% corresponding to 1.64σ, so that the measured spectrum deviates from the 1/L2 law at a confidence level ~90%. The measured energy spectrum deviates from the predicted one at a similar confidence level ~90%. That both deviations are best described with oscillation parameters in the same regions of $$\Delta m_{{14}}^{2} \approx 0.7{\text{-}}0.8$$ eV2and $${{\sin }^{2}}2{{\Theta }_{{14}}} \approx 0.10{\text{-}}0.15$$ boosts the overall confidence level to ~95% (2σ). These results suggest that antineutrinos oscillate to a sterile state, but still fall short of reliably establishing the oscillation phenomenon. At present, the possibility of mimicking the oscillation effect by systematic errors cannot be completely excluded.

With the help of a flame signal sensor and a brightness sensor, the effects of the initial gasoline vapor concentration on the flame speed, brightness and zone thickness of gasoline-air explosion were studied by carrying out experiments in a closed tunnel. Results showed that the flame speed fluctuated in the test tunnel during the explosion propagation process and maximum of flame speed under different initial gasoline concentrations appeared within the anterior 1/3 of the test tunnel. The maximum flame speed first increased and then decreased with the increase of the initial gasoline vapor concentration. Due to the existence of flame oscillation phenomenon in the explosion process, experimental data of the flame zone thickness were greater than their actual values. Based on reasonable simplifications and assumptions of the flame oscillation phenomenon, the data of the flame zone thickness in accordance with the actual situation were calculated. Results also showed that the flame zone thickness first increased and then decreased with the increase of initial gasoline vapor concentration. The flame brightness increased with the increase of the initial gasoline vapor concentration when the initial gasoline vapor concentration was set at a lower level (less than 1.7%), and when the initial gasoline vapor concentration was greater than the stoichiometric concentration, the flame brightness reduced with the increase of initial gasoline vapor concentration. However, when the initial gasoline vapor concentration further increased to a higher level (higher than 2.1%), the flame brightness increased again with increasing of initial gasoline vapor concentration.

Nappe oscillation and its potentially undesirable impact associated with significant noise production can be an issue for free-overfall hydraulic structures. Although nappe oscillation has ...

To investigate the oscillation phenomenon caused by renewable energy integration, the ac-side perturbation characteristics of voltage-source converter (VSC) is studied qualitatively and quantitatively. Firstly, the propagation path of the ac-side perturbation in VSC is qualitatively analyzed. And the dq component asymmetry concept is introduced in the analyzing process, which illustrates the appearance of the complementary frequency perturbation component. Then, the quantitative relationship among the perturbation components in VSC is analyzed, specially considering the influence of the phase-locked loop (PLL). Finally, the port-impedance and the complementary frequency effect admittance of VSC are deduced, which are further verified by time-domain simulation. In addition, the influence of controller parameters on the port-impedance is also analyzed in the case study. It is concluded that the complementary frequency perturbation component is mainly caused by the PLL perturbation. And the PI parameters of PLL have a great influence on the port-impedance.

Doubly fed induction generator-based wind turbines are vulnerable to subsynchronous oscillations. Subsynchronous control interaction is a recently emerging subsynchronous oscillation phenomenon, which means the interaction between the rotor-side converter of a doubly fed induction generator-based wind turbine and a fixed series-compensated transmission line. In this article, subsynchronous control interaction is quantitatively analyzed, and an subsynchronous control interaction-triggered condition is created to detect the existence of subsynchronous control interaction. The subsynchronous control interaction-triggered condition is then combined with impedance scanning to effectively identify the induction generator effect and subsynchronous control interaction. Further, a subsynchronous control interaction-triggered damping control strategy is developed to effectively alleviate subsynchronous control interaction. The mitigation ability and the robustness of the presented control strategy are, resp...

Epidemic spreading has been widely investigated over the past decades. And voluntary vaccination has been often utilized to explore dynamical process in epidemics where vaccines are available. In this letter, we establish a framework considering conformity motivated update as well as myopic best response motivated update on a family network which is demonstrated by a two-layered network. Extensive numerical simulations are conducted to study the dynamics of epidemic spreading under the aforementioned update rules, from which we discover the oscillation phenomenon under the pure myopic best response condition and the amplitude diversification phenomenon under the mixing of conformity and myopic best response motivated conditions. Moreover, we find that smaller overlapping fraction of links on two-layered network shall promote the epidemic propagation. The current findings can shed some lights on the evolution of epidemic spreading process in the real-world scenarios.

This paper discusses a two-stage fully distributed approach for the unit commitment (UC) problem, which solves the UC of each individual unit. This approach, based on the augmented Lagrangian relaxation method (ALR) and alternating direction method of multipliers (ADMM), consists of two stages: the solution of the single-unit optimization problem and the distributed update of the multiplier. In the first stage, using the proximal term to effectively improve the oscillation phenomenon and the convergence speed of the improved distributed augmented Lagrangian relaxation method (ID-ALR). In the second stage of multiplier updating, using ADMM to solve dual subgradient problem in fully distributed way for obtaining subgradients. In addition, the multiplier is updated with the improved multiplier update strategy. Finally, the subgradients are also used to reduce the constraint violation degree of the UC and enhance the soft constraint ability of the ID-ALR. The simulation results show that the ID-ALR can not only obtain high-quality solutions in reasonable times but also obtain good speedup in a parallel environment. The proposed ID-ALR enables each unit to keep its information secret and achieves a fully distributed solution for UC.

The electrochemical oscillation was first observed in the charging process of anolyte in VRFBs. The chronopotentiometry with current ramp results could be used to judge the appearance of electrochemical oscillation. The electrochemical oscillation could be explained in terms of the competition between the growth and the chemical dissolution of V2O5 film in the H2SO4 solution. It was possible to regular the extra power consumption resulted by the electrochemical oscillation. This work might provide new focus on the charging process of the VRFBs and guide for new methods on energy saving.

The oscillation phenomenon during droplet spreading on solid surface is studied. Simulations based on the lattice Boltzmann method with the mass processed by the volume of fluid show that the oscillation continues during the whole spreading process and the maximum oscillation value occurs at the initial phase. By observing the amplitude of droplet contour volume and liquid membrane velocity, the amplitude change is obtained. The influence of droplet characteristics on amplitude is studied. Simulated results show that the effect of kinematic viscosity on droplet oscillation is greater than that of droplet surface tension. The velocity vectors inside the droplet are also tracked to understand the oscillation.

The household appliances in buildings have increased rapidly in the recent years. However, the surge withstanding capability of these household appliances has not been increased. Therefore, it is necessary to install surge protection device (SPD) to prevent serious damage of household electrical appliances caused by the in-rushing surges. In order to avoid the oscillation phenomenon, the effective protection distance of SPDs should be addressed before installing SPDs in the buildings. This paper discussed the influence of a group of common household electrical appliances connected in parallel on the effective protection distance of an SPD to a household appliance. The surges impinging on the household appliances connected to a distribution system are analyzed using electromagnetic transient analysis software. It is found that the SPD's protection distance increases when multiple household appliances are connected in parallel. The SPD's effective protection distance for one specific household appliance, which is determined from the case in which only this household appliance is used, is a conservative value; even if other household appliances are connected with this appliance, the SPD still provides an effective protection to this specific appliance.

For incidence in the critical region, the propagation of gaussian lasers through triangular dielectric blocks is characterized by the joint action of angular deviations and lateral displacements. This mixed effect, known as composite Goos-Haenchen shift, produces a lateral displacement dependent on the axial coordinate, recently confirmed by a weak measurement experiment. We discuss under which conditions this axial lateral displacement, which only exists for the composite Goos-Haenchen shift, presents an oscillatory behavior. This oscillation phenomenon shows a peculiar behavior of light for critical incidence and, if experimentally tested, could stimulate further theoretical studies and lead to interesting optical applications., 12 pages, 4 figures

Tropical Cyclones (TCs) are an important source of freshwater for the North American continent. Many studies have tried to estimate this contribution by identifying TC-induced precipitation events, but few have explicitly diagnosed the moisture fluxes across continental boundaries. We design a set of attribution schemes to isolate the column-integrated moisture fluxes that are directly associated with TCs and to quantify the flux onto the North American Continent due to TCs. Averaged over the 2004–2012 hurricane seasons and integrated over the western, southern and eastern coasts of North America, the seven schemes attribute 7–18 % (mean $$14\,\%$$ ) of total net onshore flux to Atlantic TCs. A reduced contribution of $$10\,\%$$ (range 9– $$11\,\%$$ ) was found for the 1980–2003 period, though only two schemes could be applied to this earlier period. Over the whole 1980–2012 period, a further $$8\,\%$$ (range 6– $$9\,\%$$ from two schemes) was attributed to East Pacific TCs, resulting in a total TC contribution of $$19\,\%$$ (range 17– $$22\,\%$$ ) to the ocean-to-land moisture transport onto the North American continent between May and November. Analysis of the attribution uncertainties suggests that incorporating details of individual TC size and shape adds limited value to a fixed radius approach and TC positional errors in the ERA-Interim reanalysis do not affect the results significantly, but biases in peak wind speeds and TC sizes may lead to underestimates of moisture transport. The interannual variability does not appear to be strongly related to the El Nino-Southern Oscillation phenomenon.

Due to the low convergence speed of the conventional iterative method for solving temperature field of mass concrete with cooling pipes, the oscillation phenomenon in the process of iterative calculation was studied, and a new method, which can be used to avoid the numerical dispersion in the calculation of temperature field of mass concrete with cooling pipes and to raise the convergence speed, was put forward by improve the conventional iterative method in this paper. Using the proposed method, the concrete temperature field of the lock floor with cooling pipes during construction was simulated, and the calculated results and measured results were compared. The result show that the calculated values and measured values are in good agreement. Besides, this new method has higher convergence speed than the conventional iterative method, especially when the temperature increment of the water along the pipe is high enough, which approached maximum 10 times higher in this simulation. So this method is meaningful in the engineering application to save the calculation time.Due to the low convergence speed of the conventional iterative method for solving temperature field of mass concrete with cooling pipes, the oscillation phenomenon in the process of iterative calculation was studied, and a new method, which can be used to avoid the numerical dispersion in the calculation of temperature field of mass concrete with cooling pipes and to raise the convergence speed, was put forward by improve the conventional iterative method in this paper. Using the proposed method, the concrete temperature field of the lock floor with cooling pipes during construction was simulated, and the calculated results and measured results were compared. The result show that the calculated values and measured values are in good agreement. Besides, this new method has higher convergence speed than the conventional iterative method, especially when the temperature increment of the water along the pipe is high enough, which approached maximum 10 times higher in this simulation. So this method is meaning...

Antarctica is the focus of attention because of increasing ice melt in response to climate warming. The changes are studied using the Moderate Resolution Imaging Spectroradiometer land surface temperature dataset. A decorrelation stretch of multi-temporal monthly land surface temperature (LST) imagery for 2009, 2010 and 2011 indicated that only 11.3 percent of the variance is independent of elevation, distance from coastline, and latitude and longitude in Antarctica. The reconstructed land surface temperature imagery presents standardised values indicating the amount it deviates from elevation, distance from coastline, latitude and longitude predicted. Cluster analysis allowed the identification of residual spatial and temporal patterns termed the temperature oscillation phenomenon that comprises a significant increase of LST in the inland regions during the summer period.

In this work, we will propose some improvements and innovations for Submerged Combustion, namely a Pressurized Submerged Combustion Technology. This paper introduces the Pressurized Submerged Combustion and some basic theoretical research.To understand better gas pressure fluctuations and their influence in flame stability, a mathematical model is developed in this paper, and its particular solution is elucidated. The results show that, the variations of pressure are influenced by bubbling which is a self-excited oscillation phenomenon. Increasing the damping of liquid motion is very helpful for stabilizing pressure fluctuations. The model can be used for guidance and optimization design of Pressurized Submerged Combustion equipments.

The first ever oscillation phenomenon of a copper wire embraced inside a self-powered liquid metal machine is discovered. When contacting a copper wire to liquid metal machine, it would be swallowed inside and then reciprocally moves back and forth, just like a violin bow. Such oscillation could be easily regulated by touching a steel needle on the liquid metal surface.

Post-fault oscillations have recently been identified as being one of the main causes of maloperations of earth-fault protection in compensated MV-networks [1]. Until now, the theory regarding post-fault oscillation condition has been missing from `classical' earth-fault protection analysis, e.g. [2], where only healthy-state, inside and outside fault conditions have been considered. This paper adds this `missing piece of the puzzle' and presents the necessary theory and hand-calculation equations to analyse the post-fault oscillation condition from earth-fault protection perspective in the level required by a protection engineer.

International audience; We consider a system of two separate finite-buffer M/M/1 queues served by a single server, where the switching mechanism between the queues is threshold-based, determined by the queue which is not being served. Applications may be found in data centers, smart traffic-light control and human behavior. Specifically, whenever the server attends queue $i (Q i)$ and the number of customers in the other queue, $Q j (i, j = 1, 2; j = i)$, reaches its threshold level, the server immediately switches to $Q j$ whenever $Q i$ is below its threshold. When a served $Q i$ becomes empty we consider two scenarios: (i) non-work-conserving; and (ii) work-conserving. We present occasions where the non-work-conserving policy is more economical than the work-conserving policy when high switching costs are involved. An intrinsic feature of the process is an oscillation phenomenon: when the occupancy of $Q i$ decreases the occupancy of the other queue increases. This fact is illustrated and discussed. By formulating the system as a three-dimensional continuous-time Markov chain we provide a probabilistic analysis of the system and investigate the effects of buffer sizes and arrival rates, as well as service rates, on the system's performance. Numerical examples are presented and extreme cases are investigated.

Surge protective devices(SPDs) are widely used as a most effective means protecting the electrical and electronic equipment against overvoltages such as lightning and switching surges. When installing SPDs, it is essential that the voltage protection level provided by SPDs should be lower than the withstand voltage of the equipment being protected. But even the proper selection of SPDs are achieved, the voltage at the equipment terminal may be higher than the residual voltage of SPD due to the reflection and oscillation phenomena. This paper was focused on the investigations of the conditions for which the equipment is protected by an SPD taking into account the influences of the protective distance and type of load. The protective effects of SPD with voltage-limiting component were analyzed as functions of types of load and protective distance between the SPD and load. As a result, in the cases of long protective distances, capacitive loads and loads with high resistance, the voltage at the load terminal was significantly higher than the residual voltage of SPD. It was found that the proper installation of SPDs should be carried out by taking into account the protective distance and type of load to achieve reliable protection of electronic equipments against surges.

This paper adopts finite-element method to analyze and test the factors which influence the brake shimmy. Based on the prototype of a particular heavy truck, finite element model of the brake shimmy about drum brake is developed upon the mechanism analysis of drum brake. The reasons that drum brake has oscillation phenomenon during braking process is analyzed by simulation and calculation the transient response in this process. Tests indicate that results of finite element analysis are consistent with the conclusion of real vehicle road test.

The installation of surge protective devices (SPDs) is important for the protection of today's household appliances against in-rushing surge. The effective protection distance should be taken into account for the installation to avoid the influence of oscillation phenomenon. For household appliances, their port impedance characteristics are more complex and frequency dependent, and for some appliances, the impedance characteristics are different in operating state and nonoperating state. With the method proposed in this paper, operating state impedance characteristics of 16 different kinds of appliances are measured and the equivalent circuits are obtained by vector fitting and circuit synthesis. The protection effect of SPDs is simulated by electromagnetic transient analysis software using a practical distribution system model, and the effective protection distances of SPDs with different protection level for these appliances are obtained. Several analyses are made about relationships between the protection distance and factors such as the type of appliance, operating condition, and protection level. A case of protection for multiappliance is also analyzed.

Up-to-date regional and local assessments of changing climate extremes are important to allow countries to make informed decisions on mitigation and adaptation strategies, and to put these changes into a global context. A workshop for countries from the Indo-Pacific region has brought together daily observations from 13 countries for an analysis of climate extremes between 1971 and 2005. This paper makes use of the workshop outcomes and post-workshop analyses to build on previous work in Southeast Asia to update the assessment of changing climate extremes using newly available station data. We utilise a consistent and widely tested methodology to allow a direct comparison of the results with those from other parts of the world. The relationship of inter-annual variability in the climate extremes indices with sea surface temperature (SST) patterns has been investigated with a focus on the influence of the El Nino-Southern Oscillation phenomenon. The results support findings from elsewhere around the globe that warm extremes, particularly at night, are increasing and cold extremes are decreasing. Trends in precipitation extremes are less spatially consistent across the region. © Royal Meteorological Society and Crown Copyright 2010.

A capacitor current feedback pulse train (CCF-PT) control technique for switching DC–DC converters is proposed and applied to the control of a buck converter operating in continuous conduction mode (CCM). The analysis and experimental results show that the CCF-PT control technique can effectively eliminate the low-frequency oscillation phenomenon that exists in conventional pulse train (PT)-controlled CCM switching DC–DC converters.

To eliminate the low-frequency oscillation phenomenon in pulse train controlled switching DC–DC converters operating in continuous conduction mode (CCM), a valley current mode pulse train control technique is proposed. The experimental results show that by using the proposed control technique, the low-frequency oscillation in the pulse train (PT) controlled CCM switching DC–DC converter can be eliminated, while the great robustness and excellent transient performance of the traditional PT control technique can be retained.

A silicon magnetic sensitive transistor (SMST) with the negative resistance oscillation phenomenon is presented in this paper. The SMST of cubic structure is composed of three regions and three electrodes (E, C and B). Two of the regions (collector region and base region) are designed on the top surface of the SMST, and the emitter region is designed at the bottom of the SMST. Using microelectromechanical system (MEMS) technology, the chip is fabricated on [Formula: see text] orientation p-type silicon (near intrinsic) wafer and packaged on printed circuit board (PCB). When collector voltage (V[Formula: see text]) and the base injecting current (I[Formula: see text]) are a certain value, the experimental results show that the collector current (I[Formula: see text]) attains negative resistance oscillation phenomenon and it is influenced by the external magnetic field (B) and temperature (T). Based on the effect of deep-level impurities on the carrier net recombination rate, theoretical analysis demonstrates that the deep-level impurities are the main factors of the appearance for oscillations phenomenon.

Reaction of preferential CO oxidation is studied over Rh-, Pt-catalysts in a flow reactor made of quartz. In the experiments, the following parameters were monitored: catalyst bed temperature at the inlet to the catalyst bed and the outlet, residual CO content (with IR-analyzer), residual O2 content (GC analysis). In CO absence from the reaction gas, H2 is easily oxidized over Rh and Pt, and the reaction proceeds in the mode of catalytic surface ignition (CSI) with the “hot spot” at the inlet to the catalyst bed. Appearance of CO in gas at temperatures at least below 200°C leads to slow deactivation of the catalysts. The possibility of CSI mode realization under PROX conditions over a Rh-catalyst is shown. The key component of the reaction in this case is O2—its residual content in CSI mode is less than 100 ppm. It is found that in CSI mode, a decrease in temperature increases selectivity of the reaction. Disestablishment of CSI (extinction) is accompanied over a Rh-catalyst by oscillations in catalytic activity. Possible mechanism of this oscillation phenomenon is pro-posed in connection with catalyst deactivation by CO at the inlet to the catalyst bed and with CSI at the outlet.

The purpose of this article is to study the system dynamics model and startup behavior of loop heat pipe. A mathematical model in normal operation was derived from the experimental data. The model is presented as a matrix of second-order transfer functions. It is found that the system dynamics of a LHP is a variable-structure system that changes with operating conditions. The startup phenomena are studied experimentally. The startup phenomena of a LHP can be classified into four modes, based on the heat load: (1) failure mode: Q ˙ in Q ˙ min , (2) oscillating mode: Q ˙ min Q ˙ in Q ˙ crit , (3) overshoot mode: Q ˙ crit Q ˙ in Q ˙ s , and (4) normal mode: Q ˙ s Q ˙ in . For heat load Q ˙ in 40 W ( Q ˙ s ) , the overshoot phenomenon is observed. For 20 W ( Q ˙ crit ) Q ˙ in 40 W ( Q ˙ s ) , the oscillation phenomenon is observed. For Q ˙ in 5 W ( Q ˙ min ) , the startup failure is observed. All the startup behavior is of second- order.

Rainfall variability in humid West Africa (south of 8oN) is less studied than that of the Sahelian zone, the data for which are responsible for the general consensus of a downward rainfall trend in West Africa over the last few decades. Such a generalization may not be useful for modelling and planning purposes. Rainfall mechanisms in the drier Sahel and the humid Guinea Coast region differ; the former region has a single rainfall peak (in summer) but the latter region has a bi-modal seasonal distribution. It is therefore not necessarily true that a failure in the rainfall regime in one zone – and its subsequent impact on agriculture and livelihood – means the same for the other. In fact, it has been observed that a warmer South Atlantic is associated with more rainfall in the Guinea Coast region and less rainfall in the Sahel (Gu and Adler, 2003). It is also suggested that the El Nino-Southern Oscillation phenomenon (ENSO) may be more strongly associated with Sahelian rainfall than with that of the Guinea Coast region (Ward et al., 2004). Therefore there is a need to investigate rainfall trends and variability in the humid areas to better inform agricultural decision-makers. Agricultural productivity has decreased in recent decades following declining rainfall since the early 1970s, with the rainfall showing signs of improvement after 2000. This analysis will contribute to the knowledge of rainfall trends and aid in agricultural and allied industrial decision-making in this important agroclimatic zone. The study utilizes annual rainfall totals over 50 years to identify the spatial and temporal dimensions of rainfall variability in Ghana by comparing the characteristics of the period 1951 to 1970 and 1981 to 2000, hereafter referred to as P1 and P2 respectively. Specific emphasis is placed on the subhumid area of midGhana because of its national and regional significance to agricultural production and food security. Rainfall variability in Ghana

Load of the extrusion oscillates during the extrusion of high density polyethylene melt. We studied this phenomenon through the rheometry. It was concluded that in some cases this oscillation phenomenon is related with melt steady state compliance Je0 of high density polyethylene melt.

Indian summer monsoon rainfall exhibits inter-seasonal variations in the time scales of 2-7 years which are linked to quasi-biennial oscillations and El nino-Southern Oscillation phenomenon and also intra-seasonal variations in the time-scale of 30-60 days which are linked to activity of MJO which emerged as a dominant mode of intra-seasonal oscillations of Indian summer monsoon rainfall in addition to the other modes of low frequency oscillations. In this scenario, the inter and intra seasonal variability of 29 meteorological sub-divisional rainfalls has been investigated by correlating the MJO indices at 10 different longitudes covering Indian, Pacific and Atlantic Oceans with cumulative sub-divisional summer monsoon rainfall (1979 – 2000). The results were discussed.