Constant Output Rate Research Articles

A solar thermal driven ORC-VFR system employed in subtropical Mediterranean climatic building

This paper investigates the configuration of solar thermal collector driven organic Rankine cycle (ORC) utilized to power air-conditioning system of the two-story office building in Paralimni, Cyprus, through a Variable-Refrigerant-Flow (VRF) system. The reason to choose this Mediterranean climate of Paralimni, Cyprus, is due to its higher dependency on fossil fuels compared to many other countries in the EU and with a high potential of harnessing solar irradiations and demand for air-conditioning (AC) loads. This location is categorized as warm temperate zones, subtropical climates and is placed in the subcategory of Mediterranean climates with humid winters and dry summers according to climatic zone, highly demanding for air conditioning. Based on the climatic data of the study area, this system can make an effective performance. Modeling the building and estimating the AC system power consumption is carried out in the DesignBuilder. Designing the organic Rankine cycle is done with EES. A solar hot water system is designed with TRNSYS to supply the required mass flow rate of water at the desired temperature of 95 °C. In this climate, the annual surface irradiation rate is 1,793 kWh/m2 whilst the AC energy requirement of a two-story building is 7,909 kWh. The employed ORC with an internal heat exchanger is designed with a constant output rate of 3.920 kW, which delivers a total of 8,154 kWh yearly. The required heat input of the ORC is supplied by a solar hot water system, employing evacuated tube collectors. The solar system consumes a 454 kWh auxiliary heating rate per year to deliver the desired mass flow rate and outlet temperature for the ORC. As a result, the designed solar-driven ORC delivers a net of (8,154 – 454) kWh = 7,700 kWh energy each year, meaning 7,700 kWh energy saving per year, equal to 97% of VRF annual energy demand. This amount of yearly energy saving yields 2,010 USD yearly capital saving as the reward of investment in this system, and defining a 20-year project, the implementation of this solar-driven power generation system at the end of the project's lifetime would save 25,049 USD.

Energy and exergy analyses of a novel seasonal CCHP system driven by a gas turbine integrated with a biomass gasification unit and a LiBr-water absorption chiller

Combined cooling, heating, and power systems have been studied extensively because of their great potentials. Accordingly, in the present study, an innovative trigeneration system including a gas turbine cycle, a gasification unit, a heating unit, alongside a single effect absorption refrigeration cycle is proposed. The system operates on natural gas and municipal solid waste (MSW) for cooling, heating, and power generation. The designed system was simulated using Engineering Equation Solver (EES) software through two scenarios; constant power output and constant biomass feed rate, considering seasonal and annual periods. In the first scenario, considering the constant power capacity, the basic design state was considered with the biomass mixing ratio of 50%, and the results of the seasonal study showed that the system capacity is 30 MW, 41.9 MW, and 39.24 MW in terms of electricity, heating, and cooling, respectively. The exergy analysis revealed that the combustion chamber, the evaporator of Heat Recovery Steam Generator (HRSG), and the gasifier in both hot and cold seasons have the highest exergy destruction rate, while the economizers and the evaporators of both HRSGs have the lowest exergy efficiency. The constant mass flow rate of MSW was assumed to be 1.5 kg/s and accordingly, the feed rate of natural gas was also 1.5 kg/s for the mixing ratio of 50% in basic design state of the second scenario, and the results indicated that the annual average capacity of the system for electricity, heating, and cooling generation is 27.43 MW, 40 MW, and 34.15 MW, respectively. Furthermore, the system was capable of providing the domestic hot water supply of end-user with an average capacity of 7.5 MW during a year. The annual Energy Utilization Factor (EUF) and the annual exergy efficiency of the overall system were shown to be 71.25% and 30.79%, respectively.

A robust Kalman framework with resampling and optimal smoothing.

The Kalman filter (KF) is an extremely powerful and versatile tool for signal processing that has been applied extensively in various fields. We introduce a novel Kalman-based analysis procedure that encompasses robustness towards outliers, Kalman smoothing and real-time conversion from non-uniformly sampled inputs to a constant output rate. These features have been mostly treated independently, so that not all of their benefits could be exploited at the same time. Here, we present a coherent analysis procedure that combines the aforementioned features and their benefits. To facilitate utilization of the proposed methodology and to ensure optimal performance, we also introduce a procedure to calculate all necessary parameters. Thereby, we substantially expand the versatility of one of the most widely-used filtering approaches, taking full advantage of its most prevalent extensions. The applicability and superior performance of the proposed methods are demonstrated using simulated and real data. The possible areas of applications for the presented analysis procedure range from movement analysis over medical imaging, brain-computer interfaces to robot navigation or meteorological studies.

Busy periods in fluid queues with multiple emptying input states

A semi-numerical method is derived to compute the Laplace transform of the equilibrium busy period probability density function in a fluid queue with constant output rate when the buffer is nonempty. The input process is controlled by a continuous-time semi-Markov chain (CTSMC) with n states such that in each state the input rate is constant. The holding time in states with net positive output rate - so-called emptying states - is assumed to be an exponentially distributed random variable, whereas in states with net positive input rate - so-called filling states - it may have an arbitrary probability distribution. The result is demonstrated by applying it to various systems, including fluid queues with two on-off input sources. The latter exercise in part shows consistency with prior results but also solves the problem in the case where there are two emptying states. Numerical results are presented for selected examples which expose discontinuities in the busy period distribution when the number of emptying states changes, e.g. as a result of increasing the fluid arrival rate in one or more states of the controlling CTSMC.

Busy periods in fluid queues with multiple emptying input states

A semi-numerical method is derived to compute the Laplace transform of the equilibrium busy period probability density function in a fluid queue with constant output rate when the buffer is nonempty. The input process is controlled by a continuous-time semi-Markov chain (CTSMC) with n states such that in each state the input rate is constant. The holding time in states with net positive output rate - so-called emptying states - is assumed to be an exponentially distributed random variable, whereas in states with net positive input rate - so-called filling states - it may have an arbitrary probability distribution. The result is demonstrated by applying it to various systems, including fluid queues with two on-off input sources. The latter exercise in part shows consistency with prior results but also solves the problem in the case where there are two emptying states. Numerical results are presented for selected examples which expose discontinuities in the busy period distribution when the number of emptying states changes, e.g. as a result of increasing the fluid arrival rate in one or more states of the controlling CTSMC.

Low-Power System Design for MPEG-2/4 AAC Audio Decoder Using Pure ASIC Approach

This paper presents an implementation of a low-power and pure-hardware advanced-audio-coding (AAC) audio decoder system. Based on the characteristics of each decoding block, the AAC system is partitioned into four separate modules. For low-power and low-complexity considerations, architectural- and algorithmic-level approaches are adopted in both individual modules and whole system. In parallel PLA-based codeword decoder, we achieve a constant output rate of Huffman decoding in 2.5 cycles for the worst case, and memory usage is decreased compared to that in the binary-tree memory-based method. In reduced lookup table inverse quantizer, a table lookup with interpolation scheme is adopted which reduces the size of the lookup table from 8192 to 256. In hardware-shared signal processor, we use a hardware-sharing technique which integrates several similar blocks into a common hardware to reduce cost and enhance hardware utilization. In fully pipelined filterbank, a fast algorithm decreases the numbers of multiplication and addition largely to factors of 24 and 144 for the short and long blocks, respectively. A corresponding hardware for filterbank processing is proposed with fully pipelined architecture. Referring to stereo processing, a single hardware is shared for the channel pairs with low-cost consideration. The hardware operations of each module are well scheduled with high utilization of pipeline, and furthermore, the parallel processing among blocks is joined to increase efficiency. A 48% power savings can be reached by using the pipeline and parallel techniques of the channel pair. The proposed AAC decoder is realized in UMC 0.18-mum 1P6M technology and is operated at only 3 MHz in the worst case. The power dissipation is only 2.45 mW at the sampling frequency of 44.1 kHz.

Design of Memory Sub-System with Constant-Rate Bumping Process for H.264/AVC Decoder

In this paper, we propose an efficient memory sub-system and a constant-rate humping process for a H.264/AVC decoder conforming to High profile@Level 4. To efficiently utilize the throughput of external DRAM, a synchronization buffer is employed as a bridge for reformatting the read/write data exchanged between the on-chip hardware and the off-chip DRAM. In addition, we optimize the issues of read/write commands and adaptively enable the auto-precharge function by monitoring the motion information of a submacroblock. Furthermore, a regulation buffer with size comparable to the decoded picture buffer is created to ensure a constant output rate of decoded pictures for any conformed prediction structures. Along with other modules, the proposed scheme is verified at system level using transaction level modeling (TLM) technique. Statistical results show that synchronization buffer of larger block size provides higher memory efficiency, less access cycles and power dissipation. However, the granularity of 8times8 block size provides better trade-off among cost, efficiency, power, and real-time requirement

CHARACTERISTICS OF AN AEROSOL PHOTOMETER WHILE AUTOMATICALLY CONTROLLING CHAMBER DILUTION-AIR FLOW RATE

Trials were conducted to determine those factors that affect the accuracy of a directreading aerosol photometer when automatically controlling airflow rate within an exposure chamber to regulate airborne dust concentrations. Photometer response was affected by a shift in the aerosol size distribution caused by changes in chamber flow rate. In addition to a dilution effect, flow rate also determined the relative amount of aerosol lost to sedimentation within the chamber. Additional calculations were added to a computer control algorithm to compensate for these effects when attempting to automatically regulate flow based on a proportional-integral-derivative (PID) feedback control algorithm. A comparison between PID-controlled trials and those performed with a constant generator output rate and dilution-air flow rate demonstrated that there was no significant decrease in photometer accuracy despite the many changes in flow rate produced when using PID control. Likewise, the PID-controlled trials produced chamber aerosol concentrations within 1% of a desired level.

Efficient estimation of overflow probabilities in queues with breakdowns

Efficient importance sampling methods are proposed for the simulation of a single server queue with server breakdowns. The server is assumed to alternate between the operational and failure states according to a continuous time Markov chain. Both, continuous (fluid flow) and discrete (single arrivals) sources are considered. In the fluid flow model, we consider Markov-modulated fluid sources and a constant output rate when the server is operational. In the discrete arrivals model, we consider Markov-modulated Poisson sources and generally distributed service time when the server is operational. We show how known results on Markov additive processes may be applied to determine the optimal (exponentially tilted) change of measure for both models. The concept of effective bandwidth is used in models with multiple independent sources. Empirical studies demonstrate the effectiveness of the proposed change of measures when used in importance sampling simulations.

Experimental and conceptual problems in the rheological characterization of wheat flour doughs

Wheat flour dough is an industrially important material and a better understanding of its rheological behavior could have long ranging impact on the agricultural and the food processing industries. However, rheological characterization of dough is proving to be difficult due to a range of testing issues and anomalies in flow behavior. In a cone-and-plate rheometer wheat flour doughs “roll-out” of the gap before steady state viscosities can be established, as discussed by Bloksma and Nieman (1975). However, the mirror image of the transient viscosity-time plot obtained using a cone-and-plate viscometer has been used to obtain an estimate of steady shear viscosity behavior (Gleissle, 1975). To check this transient methodology for doughs, a second method, in addition to cone-and-plate transient flow, for determination of the shear viscosity, was needed. For this, capillary extrusion was chosen. Both a piston-driven and pressure driven capillary rheometer were employed. End corrections were determined to provide information on both the shear viscosity and, following Binding (1988), the extensional viscosity of the doughs. There are few data available on end corrections for doughs, though published data by Kieffer indicate that the corrections are unexpectedly very high. In this present work it was found that the end correction experiments were very difficult and imprecise in part due to the time-dependent nature of the doughs and difficulties in preparing replicate batches required to compare dies of differing L/R values. Further it was unexpectedly found that the samples, though prepared by normal mixing procedures to the “optimum” level, were so heterogeneous that large fluctuations in the pressure at constant output rate (in the piston-driven rheometer) and in output rate at constant pressure (in the pressure-driven instrument) were observed. These fluctuations could be eliminated by overmixing of the doughs, but overmixed doughs are of little practical interest. Although the problems encountered in this work were significant, it was encouraging that even these preliminary studies indicate that rheological measurements are effective in differentiating between spring and winter wheats. Defining a constitutive model for dough rheology still remains a major challenge, as results from one type of testing do not corroborate the findings from a different type of testing.

Enhancement of in vivo binding of [123I]beta-CIT by MK-801 in rat brain.

The effects of MK-801, a noncompetitive NMDA receptor antagonist, on in vivo and in vitro binding of radioactive iodine ([123I] or [125I]) labeled beta-CIT [RTI-55, 3beta-(4-iodophenyl)tropane-2beta-carboxylic acid methyl ester] were investigated in rat brain. In the in vitro binding study, 10 pM of [125I]beta-CIT was incubated with either 0.03 microM or 3 microM of MK-801 at 24 degrees C for 60 min. In vitro, no alterations in [125I]beta-CIT binding in any region of rat brain slices were detected after addition of MK-801. In the in vivo binding study, [123I]beta-CIT was intravenously injected into rats 30 min after intraperitoneal injection of 0.03-1 mg/kg of MK-801. The in vivo [123I]beta-CIT binding in the striatum, frontal cortex, occipital cortex, hypothalamus, and thalamus was significantly increased by pretreatment with 1 mg/kg of MK-801. Kinetic analysis using the cerebellum as a reference region revealed that the increases in in vivo [123I]beta-CIT binding induced by MK-801 were mainly due to increases in both input rate constant k3 and output rate constant k4. The results of this study indicate that the glutamatergic system, including NMDA receptor, plays an important role in regulating neurotransmission in the dopaminergic or serotonergic systems in intact brain.

Modeling of subband image data for buffer control

We develop an adaptive scheme for quantization of subband or transform coded frames in a typical video sequence coder. Using a generalized Gaussian model for the subband or transform coefficients, we present a procedure to determine the optimum dead-zone quantizer for a given entropy of the quantizer output symbols. We find that, at low bit rates, the dead-zone quantizer offers better performance than the uniform quantizer. The model is used to develop an adaptive procedure to update the quantizer parameters on the basis of the state of a channel buffer with constant output rate and variable input rate. We compare the accuracy of the generalized Gaussian model in predicting the actual bit rate to that achievable using the simpler and more common Laplacian model. Experimental results show that the generalized Gaussian model has superior performance than the Laplacian model, and that it can be effectively used in a practical scheme for buffer control.

Upper and lower bounds for the multiplexing of multiclass Markovian on/off sources

In this paper, we consider a multiplexer with constant output rate and infinite buffer capacity fed by independent Markovian fluid on/off sources. We do not suppose that the model is symmetrical: there is an arbitrary number K of different traffic classes, and for each class k, an arbitrary number Nk of sources of this class. We derive lower and upper bounds for the stationary distribution of the backlog X of the form B exp(−θ∗x) ≤ P(X > x) ≤ C(θ) exp(−θx), with 0 ≤ θ ≤ θ∗. When K = 2 or K = 1, we numerically compare our bounds to the exact distribution of X and to other previously known results. Through various examples, we discuss the behavior of P(X > x) and the tightness of the bounds.

Upper and lower bounds for the multiplexing of multiclass Markovian on/off sources

In this paper, we consider a multiplexer with constant output rate and infinite buffer capacity fed by independent Markovian fluid on/off sources. We do not suppose that the model is symmetrical: there is an arbitrary number K of different traffic classes, and for each class k, an arbitrary number N k of sources of this class. We derive lower and upper bounds for the stationary distribution of the backlog X of the form B exp(−θ ∗x ) ≤ P( X > x) ≤ C(θ) exp(− θx), with 0 ≤ θ ≤ θ ∗ . When K = 2 or K = 1, we numerically compare our bounds to the exact distribution of X and to other previously known results. Through various examples, we discuss the behavior of P( X > x) and the tightness of the bounds.

Heavy traffic analysis of a storage model with long range dependent On/Off sources

We consider a fluid queueing system with infinite storage capacity and constant output rate offered a superposition ofN identical On/Off sources, where the ratio of input to output rate is small. The On and/or Off periods have heavy tailed distributions with infinite variance, giving rise to Long Range Dependence in the arrival process. In the limit of a large number of sources and high load, it is shown that the tail of the stationary queue content distribution is Weibullian, implying much larger queue contents than in the classical case of exponential tails. Noting that similar results were recently found by I. Norros for a storage system input by a Fractional Brownian Motion, we then show how the two models are related, thus providing a further physical motivation for the Fractional Brownian Motion model.

Time-Dependent Behavior of Fluid Buffer Models with Markov Input and Constant Output Rates

The authors study a method for the analysis of fluid buffer models with Markov input rate and constant output rate. In telecommunications applications, the constant output rate typically represents a fixed-rate transmission channel. Given the initial system state, the conditional (time-dependent) survivor function and moments of the buffer content are characterized as the solution of an integral equation. The method depends on the solution of a first passage time problem for the cumulative input process (an integrated Markov process) which is described by a Fredholm integral equation of the second kind. Under appropriate conditions, the integral equation has a Neumann series solution that can be found by successive approximations. Numerical results are presented for a specific example of a buffer shared by a number of input sources varying as independent Ornstein–Uhlenbeck diffusion processes, which may be used, for instance, as a model for statistically multiplexed variable bit-rate video.

Optimal flow control of a stochastic fluid-flow system

This paper is concerned with the optimal flow control of an ATM switching element in a broadband-integrated services digital network. We model the switching element as a stochastic fluid-flow system with a finite buffer, a constant output rate, and Markov-modulated fluid input. There is a cost of holding fluid and a reward for admitting the fluid to the buffer. We study the optimal flow control policies that minimize the fetal expected discounted cost. We analyze the problem by two different approaches and show that the optimal policy is of the turnpike type with the turnpike levels dependent on the states of the Markov-modulated source. We also state sufficient conditions under which the optimal turnpike levels are monotonic functions of the states of the Markov-modulated source. >

Stationary Analysis of a Fluid Queue with Input Rate Varying as an Ornstein–Uhlenbeck Process

The stationary probability distribution of the content of a fluid queue with constant output rate and input rate varying as an Ornstein-Uhlenbeck process is studied. Markov properties provide the set of equations for the derivation of this distribution; the consideration of its Fourier transform leads to the study of a functional equation of integral type in the complex plane. This analysis is shown to relate to that of the connected Fokker-Planck equation. Results are discussed and compared to that of a similar fluid queueing model. This study was motivated by teletrafflc problems encountered in the multiplexing of video communications with variable activity rate.

Pressure, gas content and eruption periodicity of a shallow, crystallising magma chamber

We present a model of the triggering of volcanic eruptions based on fractional crystallisation and oversaturation of volatile species in a shallow magma chamber. We calculate the overpressure in the chamber and consequent increase in its volume by deformation of the surrounding rocks as a function of the amount of crystallisation. When the overpressure reaches a value of twice the effective tensile strength of the volcanic edifice, eruption or emplacement of a dyke occurs, and the chamber returns to its original pressure and volume. We show the quantitative effects on the pressure history of the form of the solubility law (depending on the volatile species present), the crystallisation contraction and the presence of some initial mass of gas at t = 0. The most important of these is the solubility law. We show that, once saturated, the more soluble is the volatile species, the more important it is for the development of overpressure in the chamber. Only a few per cent fractional crystallization are required to cause overpressures equal to the fracture criterion for a pure H 2O gas phase. A pure CO 2 gas phase connot cause important overpressures because it is much less soluble. Only for the improbable case of a pure CO 2 gas phase and a large crystallisation contraction do underpressures arise. We calculate the volumetric deformation of the surroundings and the erupted volume of lava as a fraction of the chamber volume. In the cases of Kilauea and Krafla volcanoes where the volume of the magma chamber is known approximately, our results are close to observations of both the amounts of tumescence and volumes of melt ejected from the chamber. In this model the repose time between eruptions is determined by the rate of crystallisation. Estimates for the time required to reach overpressures equal to the fracture criterion are on the order of a few years for basaltic melts and a few hundred years for more viscous systems. Over the course of many eruptions this model predicts an approximately constant output rate of lava. If the chamber is a closed system, after an eruption, the amount of liquid ejected is replaced by an equivalent volume of gas. The amount of gas builds up with each successive eruption and eventually the magma chamber roof can become unstable causing caldera collapse.

Contrasting magma types and steady-state, volume-predictable, basaltic volcanism along the Great Rift, Idaho

Research Article| May 01, 1986 Contrasting magma types and steady-state, volume-predictable, basaltic volcanism along the Great Rift, Idaho MEL A. KUNTZ; MEL A. KUNTZ 1U.S. Geological Survey, M.S. 913, Box 25046, Federal Center, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar DUANE E. CHAMPION; DUANE E. CHAMPION 2U.S. Geological Survey, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar ELLIOTT C. SPIKER; ELLIOTT C. SPIKER 3U.S. Geological Survey, Reston, Virginia 22092 Search for other works by this author on: GSW Google Scholar RICHARD H. LEFEBVRE RICHARD H. LEFEBVRE 4Department of Geology, Grand Valley State College, Allendale, Michigan 49401 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1986) 97 (5): 579–594. https://doi.org/10.1130/0016-7606(1986)97<579:CMTASV>2.0.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation MEL A. KUNTZ, DUANE E. CHAMPION, ELLIOTT C. SPIKER, RICHARD H. LEFEBVRE; Contrasting magma types and steady-state, volume-predictable, basaltic volcanism along the Great Rift, Idaho. GSA Bulletin 1986;; 97 (5): 579–594. doi: https://doi.org/10.1130/0016-7606(1986)97<579:CMTASV>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The Great Rift is an 85-km-long, 2- to 8-km-wide volcanic rift zone in the Snake River Plain, Idaho. Three latest Pleistocene to Holocene basaltic lava fields, Craters of the Moon, Kings Bowl, and Wapi, are located along the Great Rift. The Craters of the Moon lava field is a composite of more than 60 lava flows, 25 cinder cones, and at least 8 eruptive fissure systems. It covers 1,600 km2 and contains ∼30 km3 of lava flows and associated pyroclastic deposits. Field, radiocarbon, and paleomagnetic data show that the Craters of the Moon lava field formed in eight eruptive periods, each of which was typically several hundred years or less in duration and was separated from others before and after by intervals of several hundred to several thousand years. The first eruptive period began ∼15,000 yr B.P., and the latest eruptive period ended ∼2100 yr B.P. The small Kings Bowl lava field (3.3 km2, 0.01 km3) and the larger Wapi lava field (330 km2, 6 km3) both formed ∼2250 yr B.P.Three magma types have fed flows along the Great Rift. The types are (1) a contaminated type that has a SiO2 range of ∼49%–64% and commonly shows petrographic evidence of contamination, (2) a fractionated type that has a SiO2 range of ∼44%–54% and shows no evidence of contamination and whose chemical and mineralogical variation can be accounted for mainly by crystal fractionation, and (3) a Snake River Plain type that has a SiO2 range of ∼45%–48%, shows little evidence of fractionation, and is represented by Kings Bowl–Wapi flows and olivine basalts of the Snake River Plain. The contaminated and fractionated magma types were erupted at the Craters of the Moon lava field, and the Snake River Plain magma type was erupted at the Kings Bowl and Wapi lava fields. These relations imply that the magma reservoirs are spatially isolated.The magma output rate for the Craters of the Moon segment of the Great Rift was constant at ∼1.5 km3/1,000 yr for the period from 15,000 to 7000 yr B.P. The rate increased to ∼2.8 km3/1,000 yr from 7000 to 2000 yr B.P., mainly as a result of the addition of contaminated magma to the nearly constant output rate of fractionated magma. The Craters of the Moon segment of the Great Rift has experienced quasi-steady-state, volume-predictable volcanism for the last 15,000 yr. The recurrence interval of eruptive activity for the Craters of the Moon lava field ranges from several hundred to ∼3,000 yr. Because the present interval has lasted ∼2,100 yr, another eruptive period seems likely to occur within the next 1,000 yr. The steady-state, volume-predictable relationship suggests that 5–6 km3 of lava will be erupted in the next eruptive period. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.