Consecutive sliding window systems

This paper proposes a new model that generalizes the linear multi-state sliding window system to the case of m consecutive overlapping windows. In this model the system consists of n linearly ordered multi-state elements. Each element can have different states: from complete failure up to perfect functioning. A performance rate is associated with each state. The system fails if in each of at least m consecutive overlapping groups of r consecutive elements (windows) the sum of the performance rates of elements belonging to the group is lower than a minimum allowable level. An algorithm for system reliability evaluation is suggested which is based on an extended universal moment generating function. Examples of evaluating system reliability and elements' reliability importance indices are presented.     

Policy innovation and emergence of innovative health technology: The system dynamics modelling of early COVID-19 handling in Indonesia

This article examines policy innovation, emergence of innovative health technology and its implication for a health system. The complexity of policy innovation implementation resulting from mixing public health resolution and economic interest will trigger the emergence of innovative health technology, which implies a health system improvement. The findings revealed that: First, policy innovation based on a science-mix category created the complexity of policy enforcement, affected the scale and speed of COVID-19 transmissions, and triggered the emergence of health innovative technology. Second, despite policy innovation in early COVID-19, handling was relatively less successful due to restricting factors in policy implementation but provided a new market for the emergence of innovative health technology. Third, the emergence of innovative health technology has strengthened health system preparedness during the pandemic, and provide an opportunity to re-examine the strengths and deficiencies of an entire health system for better health care.     

Vapor-liquid equilibria for the ternary system N2 + CO2 +n-C4H10 at 250 and 270 K1

The system studied was nitrogen + carbon dioxide +n-butane at 250 and 270 K and at pressures from 1.5 to 14 MPa. The Peng-Robinson equation was used to model the results, since it is the most widely accepted equation of state in the gas processing industry. In general, the predictions are most accurate at low and moderate pressures and poorest at high pressures, especially near the critical region.     

Synthesis of small crystal zeolite beta in a biphasic H2O-CTAB-alcohol system

Small crystal zeolite Beta with SiO₂/Al₂O₃ ratios ranging from 30 to 400 has been synthesized in a biphasic H₂O-CTAB-Alcohol system using colloidal precursor which contains secondary building units of zeolite Beta as the silica and aluminum sources. The experimental results evidenced that the synthesis system employed here resulted in readily the formation of small crystal size zeolite Beta, and the crystallite aggregates consisting of many small particles with size close to the range of nanometer were obtained. The obtained zeolite Beta samples synthesized in the biphasic system displayed higher catalytic activity for n-hexane hydrocracking than that synthesized in single aqueous system.     

Visualization of system dynamics using phasegrams

A new tool for visualization and analysis of system dynamics is introduced: the phasegram. Its application is illustrated with both classical nonlinear systems (logistic map and Lorenz system) and with biological voice signals. Phasegrams combine the advantages of sliding-window analysis (such as the spectrogram) with well-established visualization techniques from the domain of nonlinear dynamics. In a phasegram, time is mapped onto the x-axis, and various vibratory regimes, such as periodic oscillation, subharmonics or chaos, are identified within the generated graph by the number and stability of horizontal lines. A phasegram can be interpreted as a bifurcation diagram in time. In contrast to other analysis techniques, it can be automatically constructed from time-series data alone: no additional system parameter needs to be known. Phasegrams show great potential for signal classification and can act as the quantitative basis for further analysis of oscillating systems in many scientific fields, such as physics (particularly acoustics), biology or medicine.     

Random dynamic analysis of a train-bridge coupled system involving random system parameters based on probability density evolution method

The development of high-speed railway has made it important to clarify the influence of random system parameters (i.e. vehicle load, elastic modulus, damping ratio, and mass density of bridge) on train-bridge dynamic interactions. The probability density evolution method (PDEM), a newly developed theory which is applicable to train-bridge systems, can capture instantaneous probability density functions of dynamic responses. In this study, PDEM is employed to implement random dynamic analysis of a 3D train-bridge system subjected to random system parameters. The number theory method (NTM) is employed to choose the representative point sets of random parameters, whose initial probability distribution is divided by Voronoi cells., MATLAB® software is prepared for calculation, the Newmark-β integration method and the bilateral difference method of TVD (total variation diminishing) are adopted for solution. A case study is presented in which the train travels on a three-span simply supported high-speed railway bridge. The calculation accuracy and computational efficiency of the PDEM has been verified and some conclusions are provided. Furthermore, the influence of train speed under various combinations of random parameters is beyond discuss.     

An evaluation method for small-scale conduction cooled SMES cryogenic cooling system based on thermal analysis

The current flowing through a SMES is subjected to variations at a rate ranging from 0.1 A/s to 300 A/s under the influence of the power grid. The duration of power exchange varies from milliseconds to minutes, even to hours. When operating, the impact of AC losses in HTS tapes on the cryogenic cooling system should be considered. If the cryogenic cooling system fails to take away the generated heat effectively, this may lead to the temperature rise of the magnet and its possible damage. Therefore, it is essential to evaluate the technical and economical characteristic of cryogenic cooling system. Thus, a 5 MJ SMES model is built to calculate the temperature characteristic. A new factor δ is defined to assess the technological and economical validity of the chosen cryogenic scheme. The suitable capacity of the cryogenic cooling system is evaluated for different applications. The effect of the operating temperature on the technical and economical factor is also discussed.     

Identification of intermittent control in man and machine

Regulation by negative feedback is fundamental to engineering and biological processes. Biological regulation is usually explained using continuous feedback models from both classical and modern control theory. An alternative control paradigm, intermittent control, has also been suggested as a model for biological control systems, particularly those involving the central nervous system. However, at present, there is no identification method explicitly formulated to distinguish intermittent from continuous control; here, we present such a method. The identification experiment uses a special paired-step set-point sequence. The corresponding data analysis use a conventional ARMA model to relate a theoretically derived equivalent set-point to control signal; the novelty lies in sequentially and iteratively adjusting the timing of the steps of this equivalent set-point to optimize the linear time-invariant fit. The method was verified using realistic simulation data and was found to robustly distinguish not only between continuous and intermittent control but also between event-driven intermittent and clock-driven intermittent control. When applied to human pursuit tracking, event-driven intermittent control was identified, with an intermittent interval of 260–310 ms (n = 6, p < 0.05). This new identification method is applicable for machine and biological applications.     

Generalized ideal reference cycle for regenerative refrigeration: Part 2. Adiabatic systems

A generalized ideal reference cycle for regenerative refrigeration systems is discussed. The cycle has adiabatic processes of compression and expansion. Cyclic heat addition to and rejection from the cycle occur at constant pressure or constant volume immediately preceding the regenerative thermal processes. These are assumed to occur partly at constant volume, partly at constant pressure. Equations are developed for cycle work, heat lifted, coefficient of performance and the pressure ratio: mean effective/maximum cycle pressures. Various special cases are deduced from the generalized analysis including the pseudo-Stirling and pseudo-Ericsson cycles.Results are presented for the Stirling and pseudo-Stirling cycles to illustrate the effect of volume compression ratio and regenerative effectiveness on the cycle Coefficient of Performance. The pressure ratio p_mean/p_max for the same two cycles are compared to a function of the volume compression ratio.     

Optimum thermodynamic performance of three-stage refrigerating systemsPerformance thermodynamique optimale des systémes frigorifiques á trois étages

The refrigeration efficiency, mass flows through IP and HP compressors, power input and inter-stage pressures at the optimum thermodynamic performance of three stage systems are presented graphically for the most common refrigerants, R 12, R 22 and R 717. Correlations are developed to account for the effects of subcoooing of condensate and super-heating of vapour in the evaporator, each up to 15 K. The effects of superheat up to 4 K for the vapours entering the IP and HP compressors on the system performance are also studied in order to simulate real systems more closely. The respective ranges of condensing and evaporating temperatures are taken as 273.15 to 333.15 K and 273.15 to 213.15 K, with T_h?T₁?60 K.     

M out of n inspected systems subject to shocks in random environment

Consider a parallel redundant system, consisting n components, that is subject to shocks. The shocks cause the components to fail with certain probabilities. Shocks arrival rate and components’ failure probabilities may depend on an external Markovian environment. We consider warm and cold stand-by systems. Systems’ failures are silent. The system is maintained through inspection and repair/replacement. We propose several state-dependent maintenance policies and derive system availability and cost function.     

Mediators in action: Organizing sociotechnical system change

To extend and deepen the roles of mediators in relation to sociotechnical change, this article first suggested an analytical approach which thereafter was used for analysing two cases illustrating two Swedish mediating organizations in different sectors at different time periods: the half state-/half industry funded Research Institute for Water and Air Protection, IVL, in the 1960s and 70s; and the Swedish Urban Network Association, SUNA, in the early years of the 21st century. We found that the associated sociotechnical systems changed through the actions of mediators and their organization of time-spatial specific settings. The mediator concept contributed to our understanding of these changes through a number of visible processes of translating rather than transferring specific knowledge, by functioning as a single entrance to knowledge, by supporting the selection processes, and sometimes by bridging knowledge in unforeseen ways. Overall, the mediating actors took on roles to promote the system and encouraged actors within the system to connect and develop both the system as such.     

Preparation of porous polyacrylonitrile fibers by electrospinning a ternary system of PAN/DMF/H2O

Polyacrylonitrile (PAN) porous fibers were prepared in one step by electrospinning a ternary system of PAN/N, N-dimethylformamide (DMF)/water at ambient environment. The formation of porous structures was mainly due to the spinodal decomposition phase separation occurred during the electrospinning process. The concentration of PAN varied from 3 to 10 wt.% with the water content changing from 2 to 8 wt.%. When PAN concentration was above 5 wt.%, the composition of the ternary system was close to the “cloud point” and fibers with porous structures were obtained. In addition, the surface tension and viscosity of PAN solutions increased with water which may lead to the diameter increase of the fibers. The Brunauer-Emmett-Teller (BET) surface area of porous PAN nanofibers obtained from 8 wt.% PAN solution containing 7 wt.% of water was 46.4 m² g⁻¹, which was 3 times higher than that of nonporous PAN nanofibers prepared under the same conditions from a solution without water.     

Multi-objective optimization of linear multi-state multiple sliding window system

This paper considers the optimal element sequencing in a linear multi-state multiple sliding window system that consists of n linearly ordered multi-state elements. Each multi-state element can have different states: from complete failure up to perfect functioning. A performance rate is associated with each state. The failure of type i in the system occurs if for any i (1≤i≤I) the cumulative performance of any r_i consecutive elements is lower than w_i. The element sequence strongly affects the probability of any type of system failure. The sequence that minimizes the probability of certain type of failure can provide high probability of other types of failures. Therefore the optimization problem for the multiple sliding window system is essentially multi-objective. The paper formulates and solves the multi-objective optimization problem for the multiple sliding window systems. A multi-objective Genetic Algorithm is used as the optimization engine. Illustrative examples are presented.     

Linear m-gap-consecutive k-out-of-r-from-n:F systems

This paper proposes a new model that generalizes the linear consecutive k-out-of-r-from-n system. In this model the system consists of n linearly ordered statistically independent identical elements and fails if the gap between any pair of groups of r consecutive elements containing at least k failed elements is less than m elements. An algorithm for system reliability evaluation is suggested, which is based on an extended universal moment generating function. Examples of system reliability evaluation are presented.     

Improvements to the ?-α porous compaction model for simulating impacts into high-porosity solar system objects

We describe improvements to the ?-α porous compaction model for simulating solar system impacts. To improve the treatment of highly porous materials, we modified the ?-α model to account for thermal expansion of the matrix during compaction. We validated the improved model by demonstrating good agreement between numerically computed Hugoniot curves for porous iron (up to initial porosities of ∼80%) using the improved ?-α model and experimentally-derived Hugoniot data. Moreover, we verified that the model improvements are easily implemented into a hydrocode and preserve the efficiency advantage of a strain-based compaction function. We used the improved ?-α porous compaction model in the iSALE hydrocode to reproduce 2-km/s porous-target laboratory impact experiments. The simulation results were in qualitative agreement with the experiments but produced craters that were consistently deeper and larger in volume than the experiments. The results of the hydrocode simulations and laboratory experiments show a reduction in crater efficiency with increasing porosity. This reduction is more dramatic if the impactor density and velocity are higher.     

Performance optimization of three-heat-source irreversible refrigerators based on a new thermo-ecological criterion

This paper presents an optimization study of an irreversible refrigeration absorption system based on a new thermo-ecological criterion. The considered objective function is the ecological coefficient of performance (ECOP). It takes into account the first and second law of thermodynamics and is defined as the cooling load per unit loss rate of availability. The ecological coefficient of performance has been expressed and maximized according to the temperatures of the working fluid in the main components of the system. The corresponding optimal temperatures and other optimum performance parameters have been derived analytically, and the effects of the internal irreversibility, the heat leakage coefficient and the source temperature ratio on the global and optimal performances are discussed. The results show that the maximum coefficient of performance (COP) and ecological coefficient of performance (ECOP) occurs for the same operating conditions.     

Physical and electrochemical properties of Pt-Ru/C samples prepared on various carbon supports by using the barrel sputtering system

The present study investigated physical and electrochemical properties of carbon-supported Pt-Ru alloy (Pt-Ru/C) samples prepared on various carbon supports by using a sputtering system with barrel-type powder sample holder (the barrel sputtering system). For this system, the deposited Pt-Ru nano-particles had uniform sizes of less than 4 nm and homogeneous atomic ratios of Pt and Ru of ca. 50:50 at.% independent of a specific surface area of the carbon support. Further, the electrochemical properties of the prepared samples obtained from CO stripping voltammetry were almost identical. These were completely different from the result for wet process showing that the physical and electrochemical properties of samples prepared by an impregnation method changed with the specific surface area of the carbon support.     

Frequency response of lift control in Drosophila

The flight control responses of the fruitfly represent a powerful model system to explore neuromotor control mechanisms, whose system level control properties can be suitably characterized with a frequency response analysis. We characterized the lift response dynamics of tethered flying Drosophila in presence of vertically oscillating visual patterns, whose oscillation frequency we varied between 0.1 and 13 Hz. We justified these measurements by showing that the amplitude gain and phase response is invariant to the pattern oscillation amplitude and spatial frequency within a broad dynamic range. We also showed that lift responses are largely linear and time invariant (LTI), a necessary condition for a meaningful analysis of frequency responses and a remarkable characteristic given its nonlinear constituents. The flies responded to increasing oscillation frequencies with a roughly linear decrease in response gain, which dropped to background noise levels at about 6 Hz. The phase lag decreased linearly, consistent with a constant reaction delay of 75 ms. Next, we estimated the free-flight response of the fly to generate a Bode diagram of the lift response. The limitation of lift control to frequencies below 6 Hz is explained with inertial body damping, which becomes dominant at higher frequencies. Our work provides the detailed background and techniques that allow optomotor lift responses of Drosophila to be measured with comparatively simple, affordable and commercially available techniques. The identification of an LTI, pattern velocity dependent, lift control strategy is relevant to the underlying motion computation mechanisms and serves a broader understanding of insects'' flight control strategies. The relevance and potential pitfalls of applying system identification techniques in tethered preparations is discussed.