Permissible Time Research Articles

An Approach to the Assessment of Voltage Quality Based on a Modified Power Acceptability Curve

Starting with the Computer Business Equipment Manufacturers' Association acceptability curves, a procedure for quantifying the voltage quality is proposed. It is based on using the reciprocal of the permissible time duration for each value of the customer voltage. Since the magnitude of the voltage at any network bus changes with time depending on the load curve, the daily average value of the above suggested voltage quality index will provide a suitable figure of merit for the quality assessment. The analysis starts with the derivation of an analytical expression of the voltage quality index, denoted as voltage penalty function, in terms of the voltage. Then, relations are presented for the dependence of this index on the network as well as of the load parameters. Special interest is given to the load factor, the load power factor, its peak value, and the short-circuit level of the power network. The impact of eventual shunt compensation (and its level) on the voltage quality is discussed for both permanently connected capacitors, and for those which are switched only for a certain duration. In the latter case, the effect of the capacitor switching time point is demonstrated. The compensation level, the time point of application, and its duration are the three parameters for which a detailed sensitivity analysis and optimization for the least voltage daily average penalty are conducted. The applicability of the suggested procedure to nonrepeated events in distribution networks is also addressed

Exhumation of Greater Himalayan rock along the Main Central Thrust in Nepal: implications for channel flow

Abstract South-vergent channel flow from beneath the Tibetan Plateau may have played an important role in forming the Himalaya. The possibility that Greater Himalayan rocks currently exposed in the Himalayan Fold-Thrust Belt flowed at mid-crustal depths before being exhumed is intriguing, and may suggest a natural link between orogenic processes operating under the Tibetan Plateau and in the fold-thrust belt. Conceptual and numeric models for the Himalayan-Tibetan Orogen currently reported in the literature do an admirable job of replicating many of the observable primary geological features and relationships. However, detailed observations from Greater Himalayan rocks exposed in the fold-thrust belt’s external klippen, and from Lesser Himalayan rocks in the proximal footwall of the Main Central Thrust, suggest that since Early Miocene time, it may be more appropriate to model the evolution of the fold-thrust belt using the critical taper paradigm. This does not exclude the possibility that channel flow and linked extrusion of Greater Himalayan rocks may have occurred, but it places important boundaries on a permissible time frame during which these processes may have operated.

The selection and scheduling of telecommunication calls with time windows

We consider the bandwidth scheduling problem that consists of selecting and scheduling calls from a list of available calls to be routed on a bandwidth-capacitated telecommunication network in order to maximize profit. Each accepted call should be routed within a permissible scheduling time window for a required duration. To author's knowledge, this study represents the first work on bandwidth scheduling with time windows. We present an integer programming formulation of the problem. We also propose a solution procedure based on the well-established Lagrangean relaxation technique. The results of extensive computational experiments over a wide range of problem structures indicate that the procedure is both efficient and effective.

Effects ofTemporary Clips on Somatosensory Evoked Potentials in Aneurysm Surgery

Changes in somatosensory evoked potentials (SEPs) were used to identify cerebral ischemia and to predict neurological outcome during the application of temporary clips in aneurysm surgery. SEPs were recorded intra-operatively in 76 patients with 79 aneurysms (8 in the posterior fossa). Twenty aneurysms ruptured during surgery, and 37 temporary clips were applied over an average of 8.1 minutes (range: 2-25 minutes). Of 17 cases with complete loss of potential, 14 were associated with temporary clips. Two losses were persistent with postoperative neurological deficit after 10 minutes of clipping. Six showed incomplete recovery after a mean loss of 19.2 minutes following clipping of 9.3 minutes, resulting in a new deficit in four patients. Despite complete recovery of potential in six patients after a 1 loss over 18.8 minutes following clipping of 10.7 minutes, four patients developed neurological deficits. The sensitivity of SEPs in determining permanent neurological deficits was 57%, and the was specificity 88%. The duration of temporary clipping was significantly shorter in patients without resulting new neurological deficit (Mann-Whitney Test; p < 0.01). The risk of a new deficit was 30.7% in cases where less than 8 minutes of clipping was performed, and the risk was 80.9% when clipping exceeded 8 minutes. The extent of recovery of potentials and the duration of SEP changes was strongly associated with the postoperative deficits (Kolmogorov-Smirnov Test, p = 0.009; p = 0.001, Mann-Whitney Test). Pathological p(ti)O2 measurements were obtained in 6 of 12 patients. In four patients, temporary occlusion was followed by a parallel alteration of SEPs and p(ti)O2 below 10 mmHg. There is no genuinely safe permissible occlusion time. Despite complete recovery of SEPs after a loss of potential, the patient may develop new deficits.

A Fine-Grained Coalition Access Control Policy for Jointly-Owned Resources in Collaborative Environments

Joint access to shared resources (e.g., objects, applications, and services) among autonomous domains that form a coalition has recently become important in both military and commercial areas. The brass tacks in coalition are that these domains have different self-interests although they focus on achieving a common goal. In this paper, to enable effective protection of jointly-owned resources, the notion of trust into coalition access control is built, and a fine-grained access control policy based on quantifying permission idea is proposed. The usage format of permission in this policy is meta-permission that is a share of access permission to coalition resources and is owned by multiple domain users. When accessing jointly owned resources, the sum of participants’ meta-permission value must attain a predefined permission quantity called “permission-threshold” and an assigned participant member number. In addition, permissible time span of the meta-permission is also taken into account to achieve the above goals and access requesting time must fall into their common permissible time span. Doing this enables the coalition to retain control over the access to coalition resources in distributed environments. Lastly, the preserving security property of the fine-grained access control policy with respect to state transition is proven.

Efficient techniques for improved QoS performance in WDM optical burst switched networks

In this paper, we address the problems of burst scheduling, network fairness, and service differentiation in wavelength division multiplexing (WDM) optical burst switched (OBS) networks. We propose two approaches— time-slotting and burst fragmentation—to provide efficient solutions for the above problems. We also propose a path selection algorithm to distribute label switched paths (LSP) based on load balancing. Time slotting refers to the quantization of time into slots of fixed sizes. Time slotting aids fast implementation of scheduling algorithms. Further, the slotting is local to the nodes and they need not be synchronized across the network. In burst fragmentation, a burst is fragmented instead of being dropped if it cannot be accommodated on any wavelength as a whole. These fragments are then sent on different wavelengths on the same path. Only in the event, that a fragment cannot be scheduled on any wavelength of the link, is the burst dropped. We develop a new scheduling algorithm based on time-slotting and fragmentation. This algorithm has several attractive features such as fast and simple implementation and improved burst dropping performance. Using the hop-based shortest path algorithm to route a burst without accounting for the link load results in poor burst dropping performance. This is because, some links could be heavily loaded forming a bottleneck for network performance. Load balancing approach aims at reducing the bottleneck of data traffic in the network. We develop a path selection algorithm based on load balancing with the objectives of improving network performance in terms of burst dropping probability and improve fairness among bursts traversing paths of different lengths. We then develop an offset-based algorithm to provide inter-class service differentiation and intra-class fairness for the bursts belonging to classes with different levels of priority. An attractive feature of this algorithm is that it works with a constraint of maximum permissible initial offset time in order to reduce the burst transfer delay and also to reduce the buffer requirements at the ingress edge routers. It also ensures that shorter-hop bursts of a low-priority class does not perform better than the longer-hop bursts belonging to a high-priority class. Extensive simulation results have been used to demonstrate the effectiveness of the proposed approaches and algorithms for various identical and non-identical traffic demand scenarios.

When Migrants Overstay Their Legal Welcome: A Proposed Solution to the Guest-Worker Program

A number of developed countries have implemented guest-worker programs in recent decades. Its basic feature is the temporary presence of the foreign guest-workers. The problem with such programs is that there is little to prevent these guest-workers from entering the illegal job market and overstaying their legal welcome, which is the reason why these programs became unpopular over time. This paper argues that a well-designed guest-worker program could be acceptable to host countries and could be beneficial for all parties concerned. It presents a host country immigration policy that tries to achieve these objectives by raising the likelihood that guest-workers return to their home country when the permissible time period elapses, and that reduces the number of immigrants entering the country illegally. The policy has three components and is based on legal responsibility by the guest-workers, new insurance markets, and cooperation with the sending country or countries.

A Two-Level Time-Stepping Method for Layered Ocean Circulation Models

This paper describes a numerical method with two time levels for solving partial differential equations that represent layered models of ocean circulation. The method is designed to be used with a barotropic–baroclinic splitting that separates the fast and slow motions into subsystems that are solved by different techniques. With this method, some of the dependent variables are predicted and then corrected. After the initial prediction steps, all steps involve centered differencing and averaging about the midpoint of the time interval in question. The Coriolis and pressure terms are evaluated at the same time levels to avoid a first-order truncation error in the geostrophic balance between those terms. Compared to the three-level leapfrog method that is widely used in geophysical fluid dynamics, the present method does not admit a computational mode, and the maximum permissible time step is at least twice as large. In addition, with the two-level method it is possible to use a nearly nonoscillatory advection algorithm to solve the equations for mass and momentum. In a simple test problem, the present method gives less phase error than the leapfrog method and two other methods, and it does not give any amplitude error. The differences are especially large when comparing the present method to the leapfrog method. The two-level method also gives good results in a nonlinear test problem involving vanishing layers at the top and bottom of the fluid domain and an interface moving along sloping bottom topography.

Whole body vibration on helicopter pilot seat for two types of helicopters

The aim of the work was to measure the whole body vibration on helicopter pilot seats in two types of helicopters with jet engines and to accomplish the third octave analysis of whole body vibration acceleration in all three axes. The results of measurement on the first type of helicopters showed that the highest acceleration levels were in third octave band with the mid frequency of 16 Hz. The highest whole body vibration acceleration values were for the following regimes: the regime of levitation and the regime of horizontal flight with a speed of 250 km/h. The permissible exposure time periods for these acceleration levels were around 5 hours. The results of measurement on the second type of helicopters showed that the highest acceleration levels were in the third octave band with the mid frequency of 6,3 Hz. The highest whole body vibration acceleration values were for the following regimes: the regime of turning point and the regime of horizontal flight with a speed of 200 km/h. The permissible exposure time periods for these acceleration levels were around 3 hours. The acceleration levels in X or Y axes for both types of helicopters, in all regimes and all third octave bands, were very far below from the exposure levels for 24 hours. Since the pilots 'continuous exposure in the investigated regimes of flights is below these mentioned time periods, we can conclude that the whole body vibration levels do not have significant effects on the pilots' working ability.

Phosphine exposure to applicators and bystanders from rodent burrow treatment with aluminum phosphide

An industrial hygiene study was conducted to monitor levels of phosphine gas exposure of applicators and bystander environment during use of aluminum phosphide tablets where used to treat rodent burrows, or when entering treated fields and adjacent buildings. State-of-the-art Draeger Pac III monitoring units and Draeger Phosphine Badges were placed on 33 applicators using Fumitoxin® tablets to treat ground squirrels (Spermophilus spp.) and pocket gophers (Thomomys spp.). Applicators represented both frequent and infrequent users. Agricultural and urban area applicators and bystander conditions in 9 California counties were monitored. Bystander sites were monitored with the Pac III data logging equipment. Thirty concrete slab or raised foundation buildings and 9 outdoor park and almond or walnut production sites were monitored for phosphine gas. No applicator phosphine exposures were above either the permissible 8-hour Time Weighted Average (TWA) of 0.3 ppm (Permissible Exposure Limit - PEL), or the 15-minute Short Term Exposure Limit (STEL) of 1.0 ppm. Higher exposures were observed for non-certified infrequent users than for certified or non-certified frequent applicators. The average TWA for applicators was 0.035 ppm, about 10% of the PEL. Label directions are satisfactory to avoid excessive worker exposure and environmental impact. Several work practices were associated with higher exposure potential, and recommendations were made for their mitigation to further reduce exposure. All exposures to PH3 were related to poor handling procedures that could be avoided by following the label and proper training. Average PH3 levels at potential bystander sites inside and outside residences were well below the 0.3 ppm TWA. No building registered over 10% of the PEL. In the outside trials, there were only 2 Pac III readings of over 100 that indicated detectable 8-hour TWAs at ground squirrel sites. The sites were very heavily infested, and PH3 only slightly exceeded 10% of the PEL. No PH3 was detected above pocket gopher burrows in any field site. When used according to the current label, the potential PH3 exposures of applicators and bystanders are low relative to the Low Observed Adverse Effect Level and are within existing occupational standards. Training was associated with lower worker exposures of certified applicators and non-certified frequent users compared to non-certified infrequent users.

Hippocampal pyramidal cell activity encodes conditioned stimulus predictive value during classical conditioning in alert cats.

We have recorded the firing activities of hippocampal pyramidal cells throughout the classical conditioning of eyelid responses in alert cats. Pyramidal cells (n = 220) were identified by their antidromic activation from the ipsilateral fornix and according to their spike properties. Upper eyelid movements were recorded with the search coil in a magnetic field technique. Latencies and firing profiles of recorded pyramidal cells following the paired presentation of conditioned (CS) and unconditioned (US) stimuli were similar, regardless of the different sensory modalities used as CS (tones, air puffs), the different conditioning paradigms (trace, delay), or the different latency and topography of the evoked eyelid conditioned responses. However, for the three paradigms used here, evoked neuronal firing to CS presentation increased across conditioning, but remained unchanged for US presentation. Contrarily, pyramidal cell firing was not modified when the same stimuli used here as CS and US were presented unpaired, during pseudoconditioning sessions. Pyramidal cell firing did not seem to encode eyelid position, velocity, or acceleration for either reflex or conditioned eyelid responses. Evoked pyramidal cell responses were always in coincidence with a beta oscillatory activity in hippocampal extracellular field potentials. In this regard, the beta rhythm represents a facilitation, or permissive time window, for timed pyramidal cell firing. It is concluded that pyramidal cells encode CS-US associative strength or CS predictive value.

Ultraviolet Radiation Emitted by CO&lt;sub&gt;2&lt;/sub&gt; Arc Welding

The arcs associated with arc welding emit high levels of ultraviolet radiation (UVR), and this often causes acute injuries in the workplace, particularly photokeratoconjunctivitis. It is important to know the level of UVR emitted by arc welding under various conditions, as this information will help in evaluating potential UVR hazards in welding workplaces and taking protective measures against it. In this study, the ACGIH effective irradiance for UVR was measured experimentally for CO(2) arc welding in order to evaluate its UVR hazards. A welding robot was used in the experiment in order to realize reproducible and consistent welding operations. The effective irradiance at 1 m from the arc was in the range 0.28-7.85 W/m(2) (28-785 microW/cm(2)) under the study conditions. The corresponding permissible exposure time per day is only 4-100 s, suggesting that UVR from CO(2) arc welding is actually hazardous for the eye and skin. It was found that the effective irradiance is inversely proportional to the square of the distance from the arc, is strongly dependent on the direction of emission from the arc with a maximum at 50-60 degrees from the plate surface, and tends to increase with welding current.

Ultraviolet radiation emitted by CO2 arc welding

The arcs associated with arc welding emit high levels of ultraviolet radiation (UVR), and this often causes acute injuries in the workplace, particularly photokeratoconjunctivitis. It is important to know the level of UVR emitted by arc welding under various conditions, as this information will help in evaluating potential UVR hazards in welding workplaces and taking protective measures against it. In this study, the ACGIH effective irradiance for UVR was measured experimentally for CO2 arc welding in order to evaluate its UVR hazards. A welding robot was used in the experiment in order to realize reproducible and consistent welding operations.The effective irradiance at 1 m from the arc was in the range 0.28–7.85 W/m2 (28–785 μW/cm2) under the study conditions. The corresponding permissible exposure time per day is only 4–100 s, suggesting that UVR from CO2 arc welding is actually hazardous for the eye and skin. It was found that the effective irradiance is inversely proportional to the square of the distance from the arc, is strongly dependent on the direction of emission from the arc with a maximum at 50–60° from the plate surface, and tends to increase with welding current.

A bio-inspired nonlinear algorithm to integrate carbon monoxide concentration aiming to fulfil international standards

International standards for carbon monoxide (CO) alarms in domestic premises dictate the permissible alarm-triggering times for different CO concentration levels. Simple, but reliable, integration algorithms should be included in low-cost smart alarms based on microcontrollers. Here, we present a bio-inspired digital integrator and its performance is tested against American and European standards. The difficulties to fulfil the later are discussed, and some modifications of the algorithm are introduced. Finally, the admissible concentration errors are calculated.

Drawbacks of Occupational Noise Exposure Limits with Exchange Rate of 5 dB(A)

Occupational noise, particularly in noisy industrial plants is a potentially serious health problem. Therefore, to ensure the health and safety of the workers against high level occupational noise, occupational noise exposure limits of (i) 90 dB(A) L Aeq , with an exchange rate of 3 dB(A), per halving or doubling exposure time, (ii) 90 dB(A) L Aeq , with an exchange rate of 5 dB(A), (iii) 85 dB(A) L Aeq , with exchange rate of 3 dB(A) or (iv) 85 dB(A) L Aeq , with exchange rate of 5 dB(A) have been set up for industrial plants with a working schedule of 8 h/day and 5 days a week (i.e., 40 h/week), by various countries [1]. The International Institute of Noise Control Engineering, USA [1], has recommended a limit of 85 dB(A) L Aeq , with an exchange rate of 3 dB(A) per doubling or halving exposure time, normalized to 8 hours per day and 40 hours a week. The permissible exposure time per day, for the limits of 85 and 90 dB(A) L Aeq , both with exchange rate of 3 and 5 dB(A), analyzed for each dB(A) values is given in Table 1 (on following page). The approximate values of exposure time for intermediate dB(A) values for the limits of 85 and 90 dB(A) L Aeq , with exchange rate of 3 dB(A) are obtained by multiplying the exposure time of 8, 4, 2, — , — , — h/day with 0.75 and d0.625 [2]. Similarly, for these two limits, with exchange rate of 5 dB(A), the approximate values of exposure time for the intermediate dB(A) values are obtained by multiplying the exposure time of 8, 4, 2, — , — , — h/day, with

Design and implementation of a video network server

In this article, we propose a new video server method, which is an extension of an existing network file system to include video functions. Conventional network file systems cannot transfer video data in real time, because they do not have a mechanism to guarantee the video data transfer rate. Therefore, we use a new time slot method that combines the divided time slot method and the elevator seek method. Furthermore, we use a new method for sending video data from the server to the network. It performs rate control on existing network protocols that do not have rate control functionality. The result of implementation of these methods shows that the new time slot method decreases client response time to one-half to one-tenth compared with conventional methods, and we confirmed that the worst response delay by the new rate control method is within the permissible time that guarantees data transfer rate. We decreased response time for clients in our new video server method, by employing the time slot method to guarantee video data read-bit-rate from disks, we employ the time slot method to guarantee the bit rate in reading video data from disks, and we decreased the response time for clients (by using the time slot method in reading from disks).

The effect of the thermal exposure on microstructure of MP159 alloy

The effect of the thermal exposure at different temperatures on the microstructure is investigated for MP159 alloy by optical microscopy and transmission electron microscopy (TEM). Thermal exposure at 660°C is related to the aging induced hardening mechanism, thermal exposure at the neighborhood of 920°C is associated with static recrystallization behavior, and thermal exposure at a temperature range of 920 to 1070°C for a short time is investigated with a view toward obtaining the longest permissible thermal exposure time during which microstructural reconstitution of the cold deformed microstructure would not occur at the corresponding temperature, which would provide guidance for determining reasonable hot forging parameters of fasteners. The results indicate that both solution heat treated (ST) and cold worked (CW) MP159 alloy could be hardened by aging. This aging induced hardening is attributable to the precipitation of a very finely dispersed fcc ordered solid solution. The precipitating process is so rapid that the air cooling (AC) or water cooling (WC) process of the sample exposed to elevated temperature higher than normal aging temperature could produce an appreciable hardening effect. The recrystallization temperature of the alloy is as high as 920°C, such a high recrystallization temperature is attributed to deformation twins and a variety of alloying elements due to their inhibition to the nucleation and growth of recrystallization grains, other than to the hcp-phase which used to be believed to explain high recrystallization temperature in MP alloys in some literature.

Temporal restriction of MyoD induction and autocatalysis during Xenopus mesoderm formation.

In Xenopus, the activation of the myogenic determination factors MyoD and Myf-5 in the muscle-forming region of the embryo occurs in response to mesoderm-inducing factors (MIFs). Different members of the FGF, TGF-beta, and Wnt protein families have been implicated in this process, but how MIFs induce the myogenic regulators is not known. For MyoD, the induction process may serve to locally stabilize a transient burst of ubiquitous transcription at the midblastula transition, possibly by triggering MyoD's autocatalytic loop. Here we have sought to distinguish separate activating functions during MyoD induction by analyzing when MyoD responds to different MIF signaling or to MyoD autoactivation. We show that MyoD induction depends on the developmental age of the induced cells, rather than on the type or time point of inducer application. At the permissive time, de novo MyoD induction by Activin requires less than 90 min, arguing for an immediate response, rather than a series of inductive events. MyoD autoactivation is direct, but subject to the same temporal restriction as MyoD induction by MIF signaling. Further evidence implicating MyoD autocatalysis as an essential component of the induction process comes from the observation that both autocatalysis and induction of MyoD are selectively repressed by a dominant-negative MyoD mutant. In summary, our observations let us conclude that MyoD's expression domain in the embryo results from an interplay of timed changes in cellular competence, pleiotropic signaling pathways, and autocatalysis.

Effects of a maximum permissible journey time (31 h) on physiological responses of fleeced and shorn sheep to transport, with observations on behaviour during a short (1 h) rest-stop

AbstractConcern for the welfare of export lambs during long-distance road transport has prompted much research and a recommended change in procedure. The latter envisages an absolute maximum journey time of 31 h and includes a rest-stop (minimum duration 1 h) for feeding and watering. In the present experiment, the physiological and behavioural responses to this new protocol have been investigated in fleeced and shorn lambs (no. = 10 per group) provided with venous catheters and heart rate monitors. The two groups were loaded on a vehicle into separate adjacent pens and driven for 14 h; then unloaded into a lairage, where their behaviour was recorded. After 1 h they were reloaded and driven for a further 15·5 h, finally arriving at a slaughterhouse where carcass condition was evaluated. Blood samples collected at 30- or 60-min intervals by experimenters travelling with the animals were analysed to determine haematocrit, plasma osmolality, plasma concentrations of glucose, creatinine phosphokinase (CPK), and the stress-responsive hormones, cortisol, prolactin, adrenaline and noradrenaline. The results showed that haematocrit increased after loading although the general trend during transport, as with osmolality, was a decline (P &lt; 0·05). No significant changes in plasma glucose were detected but CPK increased in fleeced lambs after loading (P &lt; 0·05). Cortisol release was stimulated by loading, especially in fleeced sheep (P &lt; 0·001) but returned to home pen values within 6 h; heart rates changed in a similar manner. Transport did not markedly affect prolactin release although concentrations were consistently greater in fleeced sheep (P &lt; 0·001). Noradrenaline, however, tended to be higher in shorn animals (P &lt; 0·05). In lairage, both groups readily consumed hay, and especially concentrates, but the shorn lambs spent more time eating (P &lt; 0·001). None of the shorn sheep, and only a few fleeced animals, drank water. There was no evidence for differences in weight loss between the two groups during the experiment and carcass quality at slaughter was within the normal expected range. The implications of these, and other related studies, for future transport policy are discussed, with particular reference to rest-stop duration and handling procedures.

Design and implementation of a video network server

In this article, we propose a new video server method, which is an extension of an existing network file system to include video functions. Conventional network file systems cannot transfer video data in real time, because they do not have a mechanism to guarantee the video data transfer rate. Therefore, we use a new time slot method that combines the divided time slot method and the elevator seek method. Furthermore, we use a new method for sending video data from the server to the network. It performs rate control on existing network protocols that do not have rate control functionality. The result of implementation of these methods shows that the new time slot method decreases client response time to one-half to one-tenth compared with conventional methods, and we confirmed that the worst response delay by the new rate control method is within the permissible time that guarantees data transfer rate. We decreased response time for clients in our new video server method, by employing the time slot method to guarantee video data read-bit-rate from disks, we employ the time slot method to guarantee the bit rate in reading video data from disks, and we decreased the response time for clients (by using the time slot method in reading from disks).