Moderate Load Conditions Research Articles

Investigation on the Combustion and Emission Characteristic of Diesel Engine with EGR

Based on a diesel engine with common rail system, influence of EGR on combustion and emission characteristic were investigated. The test results show that EGR can cut down both cylinder pressure and the rate of pressure rise, which leads to the depression of instantaneous rate of heat release and combustion temperature and the extension of the whole combustion period.EGR make effective improvements on reducing NOx emissions in all the operating modes. In light load condition CO and HC emissions take a favorable turn with larger EGR rate, SOOT and fuel consumption are well maintained. In moderate and heavy load condition, the curve of HC ,CO emissions assume “hook-like”, which is get down first and then steep rise. SOOT is well maintained before the inflection point but get deteriorate after the point. As the working load rate of the engine become heavier, the rate of EGR whose inflection point located becomes smaller and the fuel consumption turn out to be worse.

Ultraviolet dust aerosol properties as observed by MARCI

Observations by the Mars Color Imager (MARCI) on board the Mars Reconnaissance Orbiter (MRO) in two ultraviolet (UV, Bands 6 and 7; 258 nm, and 320 nm, respectively) and one visible (Band 1, 436 nm) channels of the 2007 planet encircling dust storm are combined with those made by the two Mars Exploration Rovers (MERs) to better characterize the single scattering albedo ( ω 0 ) of martian dust aerosols. Exploiting the low contrast of the surface in the UV (and blue) as well as the reduced importance of surface reflectance under very dusty conditions, we utilize the sampling of photometric angles by the MARCI cross-track geometry to synthesize an analog of the classical Emergence Phase Function (EPF). This so-called “pseudo-EPF”, used in conjunction with the “ground-truth” measurements provided by the MERs, is able to effectively isolate the effects of the dust ω 0 . The motivation for this approach is the elimination of a significant portion of the type of uncertainty involved in many previous radiative transfer analyses. Furthermore, we produce a self-consistent set of complex refractive indices ( m = n + ik ) through our use of an explicit microphysical representation of the aerosol scattering properties. Because of uncertainty in the exact size of the dust particles during the epoch of the observations, we consider two effective particle radii ( r eff ) to cover the range anticipated from the literature: 1.6 and 1.8 μm. The resulting set of model–data comparisons, ω 0 , and m are presented along with an assessment of potential sources of error and uncertainty. Analysis of the Band 1 results is limited to ω 0 as a “proof-of-concept” for our approach through a comparison to contemporaneous CRISM EPF results at 440 nm. The derived ω 0 are: assuming r eff = 1.6 μ m – 0.619 – 0.626 , 0.648 , and 0.765, for Bands 6, 7, and 1, respectively; for r eff = 1.8 μ m – 0.625 – 0.635 , 0.653 , 0.769 , for the same band order. For either r eff case, the total estimated error is 0.022, 0.019, and 0.010, again for Bands 6, 7, and 1. We briefly discuss our retrievals, including the asymmetry parameter ( g) associated with our model phase functions, within the context of previous efforts, with an emphasis on the improved precision of our results compared to those in the literature. We also suggest several applications of our results, including an extension of the dust climatological record using MARCI Band 7 pseudo-EPFs outside of 2007 global dust event. Initial work on this particular application using a sample of 135 pseudo-EPFs near the MERs suggests that optical depth retrievals with a precision in the range 0.2–0.4 may be possible under moderate loading conditions (i.e., τ < 1.5).

Working memory circuitry in schizophrenia shows widespread cortical inefficiency and compensation

Background Working memory studies in schizophrenia (SZ), using functional magnetic resonance imaging (fMRI) and univariate analyses, have led to observations of hypo- or hyperactivation of discrete cortical regions and subsequent interpretations (e.g. neural inefficiencies). We employed a data-driven, multivariate analysis to identify the patterns of brain–behavior relationships in SZ during working memory. Methods fMRI scans were collected from 13 SZ and 18 healthy control (HC) participants performing a modified Sternberg item recognition paradigm with three memory loads. We applied partial least squares analysis (PLS) to assess brain activation during the task both alone and with behavioral measures (accuracy and response time, RT) as covariates. Results While the HC primary pattern was not affected by increasing load demands, SZ participants showed an exaggerated change in the Blood Oxygenation Level Dependent (BOLD) signal from the low to moderate memory load conditions and subsequent decrease in the greatest memory load, in frontal, motor, parietal and subcortical areas. With behavioral covariates, the separate groups identified distinct brain–behavior relationships and circuits. Increased activation of the middle temporal gyrus was associated with greater accuracy and faster RT only in SZ. Conclusions The inverted U-shaped curves in the SZ BOLD signal in the same areas that show flat activation in the HC data indicate widespread neural inefficiency in working memory in SZ. While both groups performed the task with similar levels of accuracy, participants with schizophrenia show a compensatory network of different sub-regions of the prefrontal cortex, parietal lobule, and the temporal gyri in this working memory task.

Implementation of multiple-pulse injection strategies to enhance the homogeneity for simultaneous low-NOx and -soot diesel combustion

The diesel combustion implemented with the use of a homogeneous lean charge has shown to produce simultaneous reduction of nitrogen oxides (NOx) and soot emissions at low-load conditions. Similarly, at higher load levels, a cylinder charge mixture weakened by the use of exhaust gas recirculation (EGR) and enhanced homogeneity has also shown to result in simultaneous reduction of NOx and soot emissions. In this study multiple-shot injection experiments have been investigated as a means to enhance the homogeneity for simultaneous low-NOx and low-soot combustion at both low- and moderate-load conditions. Up to 8 fuel injection pulses per cylinder per cycle were applied to modulate the homogeneity history. The empirical results were conducted under independently controlled EGR, intake boost, and exhaust backpressure to enhance the flexibility in adapting the engine boundary conditions towards this type of combustion. Test results have been presented in increasing the engine load up to 9 bar IMEP.

1215 九州自動車道での追従安全性の検討(OS5-2:自動車の安全技術,OS5:安全・安心・防災・環境負荷低減,オーガナイズド・セッション(OS),第18回交通・物流部門大会(TRANSLOG2009))

Characteristics of danger at express way are studied by means of traffic flow data that are taken by video camera from road side of Kyushu express way. A new index named DTC(Danger To Collision) is introduced to discuss a degree of danger to rear end coffision. Two levels of traffic load condition, heavy and moderate, are studied by using DTC. It is shown that about 40% of the vehicles run very dangerous manner in moderate traffic load condition, but only 9% in heavy load condition.

Abnormal Reactivity of the Primary Somatosensory Cortex During the Experience of Pain in Complex Regional Pain Syndrome: A Magnetoencephalograhic Case Study

A 49-year-old male worker developed persistent pain in his left wrist after work strain injuries. Clinical symptoms met with criteria for Complex Regional Pain Syndrome (CRPS) type I. In the present study, the effect of the experience of pain on the somatotopy of the primary cortical hand representation was investigated. Somatosensory evoked magnetic fields (SEF) elicited by non-painful tactile stimulation at the index finger of the affected and the unaffected hand were recorded when experiencing pain elicited by a moderate physical load condition (holding a 1.6 kg object in the hand). It was shown that MEG and subjective responses to innocuous tactile stimuli were reduced when simultaneous nociceptive stimulation was applied. These findings suggest a gating effect in the central nervous system elicited by concurrent simultaneous information from two different somatosensory modalities (pain and tactile). The results revealed the existence of nociceptive-induced plastic changes in the central nervous system associated with CRPS type I.

Resistance Against the Intrinsic Rate of Fracture Mechanics Parameters for Polymeric Materials Under Moderate Impact Loading

This study contributes towards understanding crack toughness as resistance against the intrinsic rate of fracture mechanics parameters. Up to now only few investigations have been done under moderate impact loading conditions. Based on experimental investigations using the crack resistance (R) concept, it has been shown that the stop block method combined with the multiple-specimen technique is a unique method for polymers under impact loading conditions in comparison with different R-curve methods. Other methods for the determination of R curve such as the low-blow technique are normally not applicable for polymers due to their time-dependent mechanical properties. The crack-tip opening displacement (CTOD) rate is a measurement of the rate sensibility of stable fracture process depending on the type of deformation, which can provide deep insights into the micromechanics and activation mechanisms during the fracture processes. In the polymeric materials mostly investigated, one can understand the stable crack propagation with three-stage processes; crack-tip blunting/crack initiation, non-stationary stable crack growth and steady-state stable crack growth (an equilibrium state). In this stable crack propagation, the values of normalized CTOD rate converge rapidly to a ‘matrix’-specific threshold. The stop block method in the multiple-specimen technique assures the criteria of the time-independent strain field around the crack tip and constant crack speed therewith and the J-integral is a valid toughness parameter.

POCA: pattern‐oriented channel assignment scheme for wireless cellular networks

AbstractThis paper presents a new decentralized dynamic channel allocation scheme which uses a ‘clustering’ concept to allocate channels efficiently. Simulation results show that the proposed scheme performs better than fixed channel assignment and some other dynamic channel allocation schemes under low and moderate traffic load conditions. Copyright © 2004 John Wiley &amp; Sons, Ltd.

Modelling vibrated stone columns in soft clay

The vibrated stone column technique is an economical and environmentally friendly process that treats weak ground to enable it to withstand low to moderate loading conditions. The performance of the treated ground depends on various parameters such as the strengths of the in-situ and backfill materials, and the spacing, length and diameter of the columns. In practice, vibrated stone columns are frequently used for settlement control. Studies have shown that columns can fail by bulging, bending, punching or shearing. These failure mechanisms are examined in this paper. The study involved a series of laboratory model tests on a consolidated clay bed. The tests were carried out using two different materials: (a) transparent material with ‘clay like’ properties, and (b) speswhite kaolin. The tests on the transparent material have, probably for the first time, permitted visual examination of deforming granular columns during loading. They have shown that bulging was significant in long columns, whereas punching was prominent in shorter columns. The presence of the columns also greatly improved the load-carrying capacity of the soft clay bed. However, columns longer than about six times their diameter did not lead to further increases in the load-carrying capacity. This suggests that there is an optimum column length for a given arrangement of stone columns beneath a rigid footing.

Modelling vibrated stone columns in soft clay

The vibrated stone column technique is an economical and environmentally friendly process that treats weak ground to enable it to withstand low to moderate loading conditions. The performance of the treated ground depends on various parameters such as the strengths of the in-situ and backfill materials, and the spacing, length and diameter of the columns. In practice, vibrated stone columns are frequently used for settlement control. Studies have shown that columns can fail by bulging, bending, punching or shearing. These failure mechanisms are examined in this paper. The study involved a series of laboratory model tests on a consolidated clay bed. The tests were carried out using two different materials: (a) transparent material with ‘clay like’ properties, and (b) speswhite kaolin. The tests on the transparent material have, probably for the first time, permitted visual examination of deforming granular columns during loading. They have shown that bulging was significant in long columns, whereas punching was prominent in shorter columns. The presence of the columns also greatly improved the load-carrying capacity of the soft clay bed. However, columns longer than about six times their diameter did not lead to further increases in the load-carrying capacity. This suggests that there is an optimum column length for a given arrangement of stone columns beneath a rigid footing.

Dual control packets in optical burst switching networks

Previous research has demonstrated that in a single IP-over-optical burst switched WDM (OBSWDM) node, higher-priority bursts can be successfully isolated from lower-priority bursts according to a certain user-defined isolation degree. This is achieved by allocating longer offset times (i.e., the time between the arrival of the control packet and the burst) to higher-priority bursts where the longer the offset time, the higher the degree of isolation. However, this creates a catch-22 situation in which quality of service (QoS) is achieved at the expense of a serious degradation in system performance. We present what we believe is a novel dual control-packet OBS system that aims to reduce the loss probability of the single control-packet OBS system owing to priority definitions. The dual control-packet scheme maintains the same QoS isolation degree as the single control-packet scheme but with a much reduced drop probability for lower-priority packets. Under 75% loading conditions, the drop probability for low-priority packets in the dual control QoS scheme ranges from 10 to 5 times lower compared with the single control-packet scheme depending on the situation and the presence of fiber delay lines (FDLs). The dual control-packet system is also shown to exhibit a smaller complexity measure compared with the single control-packet system for moderate loading conditions.

Differential Working Memory Load Effects after Mild Traumatic Brain Injury

The objective of this study was to explore the effects of increasing working memory (WM) processing load on previously observed abnormalities in activation of WM circuitry shortly after mild traumatic brain injury (MTBI). Brain activation patterns in response to increasing WM processing load (auditory n-back: 0-, 1-, 2-, and 3-back conditions) were assessed with fMRI in 18 MTBI patients within 1 month of their injury and in 12 healthy controls. Performance accuracy on these tasks was also measured. Brain activation patterns differed between MTBI patients and controls in response to increasing WM processing loads. Controls maintained their ability to increase activation in regions of WM circuitry with each increase in WM processing load. MTBI patients showed disproportionately increased activation during the moderate processing load condition, but very little increase in activation associated with the highest processing load condition. Task performance did not differ significantly between groups on any task condition. MTBI patients showed a different pattern of allocation of processing resources associated with a high processing load condition compared to healthy controls, despite similar task performance. This suggests that injury-related changes in ability to activate or modulate WM processing resources might underlie some of the memory complaints after MTBI.

Mobility and performance modeling in cellular communication networks

In this paper, we will show a simple analytical model for cellular communication networks performance evaluation. The model assumes a finite population of mobiles moving in a finite number of cells. A model of this type allows us to evaluate the effects on system performance of the following factors: Fixed Channel Allocation (FCA) scheme, user load, mobility and distribution of users among cells. Numerical simulation experiments show that predictions of this simple model are acceptable in a wide range of mobility and for light to moderate load conditions. A discussion about these assumptions will show that this model is well suited for future pico-cellular system analysis.

Testing the control of filamentous microorganisms responsible for foaming in a full-scale activated-sludge plant running with initial aerobic or anoxic contact zones

Effects of anoxic conditions on the growth of nocardioform actinomycetes and of aerobic conditions on growth of Microthrix parvicella in activated sludge were studied to prevent foaming caused by these filamentous microorganisms. The study was conducted on a full-scale plant consisting of three parallel lines fed with the same settled wastewater and subjected to severe foaming due to a massive growth of M. parvicella in winter and of nocardioform actinomycetes in summer. The first line was rigged with an initial contact zone (selector) and the data were compared with those observed in one of the lines without a selector. A complete suppression of the growth of nocardioforms was obtained in experiments where returned activated sludge was mixed with wastewater under both anoxic conditions and high sludge loading (11.48 kg BOD 5/kg MLSS day). Under moderate sludge loading (1.80 kg BOD 5/kg MLSS day) conditions, the selector suppressed the growth of nocardioforms but was not able to improve settlement of the sludge and prevent the growth of other flamentous microorganisms responsible for foaming, such as M. parvicella. Finally, a substantial suppression of the growth of M. parvicella was obtained in experiments where returned activated sludge was mixed with wastewater under aerobic conditions and with a high sludge loading (24 kg BOD 5kg MLSS day); as a consequence, the foaming produced by this filamentous microorganism was highly reduced.

Traffic management of a satellite communication network using stochastic optimization

The performance of nonhierarchical circuit switched networks at moderate load conditions is improved when alternate routes are made available. Alternate routes, however, introduce instability under heavy and overloaded conditions, and under these load conditions network performance is found to deteriorate. To alleviate this problem, a control mechanism is used where, a fraction of the capacity of each link is reserved for direct routed calls. In this work, a traffic management scheme is developed to enhance the performance of a mesh-connected, circuit-switched satellite communication network. The network load is measured and the network is continually adapted by reconfiguring the map to suit the current traffic conditions. The routing is performed dynamically. The reconfiguration of the network is done by properly allocating the capacity of each link and placing an optimal reservation on each link. The optimization is done by using two neural network-based optimization techniques: simulated annealing and mean field annealing. A comparative study is done between these two techniques. The results from the simulation study show that this method of traffic management performs better than the pure dynamic routing with a fixed configuration.

Flow control and routing algorithms in WAPSN

The performance evaluation of several routing algorithms and the combined effect when four levels of flow control mechanisms are operating simultaneously in a wide area packetswitched network (WAPSN) is made by discrete-event simulation. Both non-adaptive and adaptive routing algorithms are discussed, and then the fixed (non-adaptive routing technique), the shortest-queue (isolated routing technique) and the shortest-path (distributed routing technique) routing algorithms are selected and described for simulation in networks both with and without a multilevel flow control mechanism. The flow control techniques described here are the channel queue limit, the window mechanism and the input buffer limit schemes. We give results for each of the following goals: 1. (a) To evaluate and compare the network performance of the routing algorithms under light, moderate and heavy load conditions during a transient period, subject to changes in the mean arrival rate of messages in networks both with and without a multilevel flow control mechanism. 2. (b) To evaluate and compare the performance of the routing algorithms during the transition of a network protected by an end-to-end flow control mechanism to an unprotected network. 3. (c) To evaluate the effect of varying the update interval for the adaptive routing algorithms. 4. (d) To evaluate and compare the performance of the routing algorithms in response to traffic changes or link failures in a network using a multilevel flow control mechanism. 5. (e) To develop innovative simulation models involving routing algorithms and a multilevel flow control mechanism for packet-switched networks.

The performance of one organic phosphonate additive in rolling-contact fatigue

It is demonstrated that the presence of a laboratory-synthesized phosphonate additive reduces the rolling contact fatigue life compared with the base oil alone under moderate load and marginal lubrication conditions ( Λ ≈ 2). This life reduction is attributed to the chemically aggressive nature of the phosphonate additive. Measurements of the contact surfaces with this additive also showed an increase in wear rate under light-load, pure sliding conditions. It is concluded that, because of its chemical structure, this phosphonate additive may have a marked adverse effect on both wear and fatigue performance.

Effects of surface composition, environment and morphology on friction and wear: an overview

Asperity contacts provide the first line of defense against friction and wear. In typical cases, stresses acting on asperities are large enough to cause the formation of wear particles. These wear particles, depending on their chemical nature and surrounding environment, may agglomerate to result in ploughing and abrasion. Exposure of underlying clean metallic surfaces may result in lubricant degradation. In addition, even under relatively low speed sliding conditions, interfacial flash heating of asperities can lead to chemical changes in the substrate materials and reduced coverage of the surfaces by lubricant molecules. The latter can lead to premature failure under moderate loading conditions. The role of the environment in markedly affecting the durability of tribosystems will be discussed.

Analysis of small disturbances of transmission lines in dynamic stability studies

The inherent small-magnitude fluctuations of transmission line parameters, often attributed to the cause of an unstable and oscillatory behaviour of electric power systems, which operate in unfaulted and normal states under moderate load conditions, are investigated. Due to the limited nature of the deterministic theory to describe the dynamics of a large-scale power system, a stochastic theory is presented. On the basis of recent mathematical studies of stochastic processes, a performance index is derived to measure the small-disturbance stability limits of the system. The viability of this performance index is tested on a power system model.

Articular contact in a three-dimensional model of the knee

This study is aimed at the analysis of articular contact in a three-dimensional mathematical model of the human knee-joint. In particular the effect of articular contact on the passive motion characteristics is assessed in relation to experimentally obtained joint kinematics. Two basically different mathematical contact descriptions were compared for this purpose. One description was for rigid contact and one for deformable contact. The description of deformable contact is based on a simplified theory for contact of a thin elastic layer on a rigid foundation. The articular cartilage was described either as a linear elastic material or as a non-linear elastic material. The contact descriptions were introduced in a mathematical model of the knee. The locations of the ligament insertions and the geometry of the articular surfaces were obtained from a joint specimen of which experimentally determined kinematic data were available, and were used as input for the model. The ligaments were described by non-linear elastic line elements. The mechanical properties of the ligaments and the articular cartilage were derived from literature data. Parametric model evaluations showed that, relative to rigid articular contact, the incorporation of deformable contact did not alter the motion characteristics in a qualitative sense, and that the quantitative changes were small. Variation of the elasticity of the elastic layer revealed that decreasing the surface stiffness caused the ligaments to relax and, as a consequence, increased the joint laxity, particularly for axial rotation. The difference between the linear and the non-linear deformable contact in the knee model was very small for moderate loading conditions. The motion characteristics simulated with the knee model compared very well with the experiments. It is concluded that for simulation of the passive motion characteristics of the knee, the simplified description for contact of a thin linear elastic layer on a rigid foundation is a valid approach when aiming at the study of the motion characteristics for moderate loading conditions. With deformable contact in the knee model, geometric conformity between the surfaces can be modelled as opposed to rigid contact which assumed only point contact.