Simultaneous Disturbances Research Articles

On the onset and meridional propagation of the ionospheric F2-region response to geomagnetic storms

The meridional propagation velocities of the ionospheric F2-region response to 268 geomagnetic storms are calculated. Ionospheric vertical sounding data of 1 h time resolution from several stations located in a longitude sector approximately centred along the great circle that contains both the geomagnetic poles and the geographic poles are used. Most meridional propagation velocities from high to low latitudes are less than 600 m/s. The smaller velocities are typical of global neutral meridional wind circulation and the larger are representative of traveling atmospheric disturbances. Simultaneous disturbances at several locations are more frequent during positive phases than during negative phases. Negative phase meridional propagation velocities associated with meridional neutral winds are less frequent in the southern hemisphere when compared with corresponding velocities observed in the northern hemisphere. This may be related to the fact that the distance between the geomagnetic pole and the equator is smaller in the northern hemisphere. Most negative phase onsets are within the 06–10 LT interval. For middle geomagnetic latitudes a “forbidden time interval” between 11 and 14 LT is present. The positive phase onsets show the “dusk effect”.

DYNAMIC ANALYSIS of the COOLING PROCESS IN PLATE HEAT EXCHANGERS

ABSTRACTThis paper describes a dynamic simulation of a mathematical model that describes the cooling process of natural orange juice in plate heat exchangers. the goal was to obtain an evaluation of the process reaction curves, represented by the behavior of the outlet orange juice's temperature after simultaneous disturbances to the following process variables: product and refrigerant fluid temperatures and mass flow rates. the simulator was encoded using the Mat‐Lab program, whose effectiveness had been previously validated (predicted values were within 2% of the published values). Assays were simulated based on the factorial design technique. the importance of variable interaction was evaluated and it was shown that each combination of disturbances to the process gave way to different effects on outlet temperature stabilization values and on the behavior of process reaction curves. the monitoring of the process variable transient behavior has been found to aid in tuning controllers throughout this process, which requires, according to the results, nonconventional coutrollers for truly efficient automation.

Optimal multiobjective planning of dynamic series compensation devices for power quality improvement

An optimisation algorithm using tabu search is presented for optimal planning of series compensation devices for power quality improvement in distribution systems. The proposed algorithm is posed for optimal placement of two types of devices, named the series voltage restorer and the fault current limiter. A multiobjective problem is formulated to optimise a composite set of fuzzy performance indices comprising the cost expenditure of installed series compensation devices, voltage boosts across sensitive loads and overall voltage improvement. To ensure robustness, distribution networks are reinforced for preselected internal fault, external fault and simultaneous disturbances. Five case studies are presented to demonstrate the properties of the proposed algorithm.

Process design and control structure screening based on economic and static controllability criteria

A method is developed that screens process flowsheet and control system configurations, defined in terms of selected controlled and manipulated variables that exhibit poor steady-state behavior under the presence of multiple simultaneous disturbances and model parameter variations. The steady-state disturbance rejection characteristics of the nonlinear process models are considered in conjunction with economic criteria for the elimination from further consideration of poor designs early in the design process. A wide variety of static control objectives for the system is incorporated within an optimization framework that evaluates the required contribution of the selected input variables to alleviate the effects of the imposed disturbances on the control objectives specified in a hierarchical order. Sensitivity information of the optimal solution to the control design problem is utilized to identify the most influential design parameters on static controllability performance, hence providing the guideline for improving the disturbance rejection properties of the flowsheet. The proposed approach allows the study of plants with unequal number of manipulated and controlled variables and the investigation of cases with saturation of manipulated variables and hard bounds on the controlled variables. The method has been applied to a number of different designs for a complex flowsheet that involves multiple reactive and separation steps with recycle. Reactive distillation configuration proved to exhibit superior economic and static controllability performance compared with the conventional reactor–separator scheme for combined reaction kinetic parameter variations.

Analysis of a Polarization-Maintaining Optical Fiber Interferometer for Simultaneous Measurement of Acoustic Pressure and Temperature

An all polarization-maintaining fiber Mach-Zehnder interferometer for simultaneous measurement of acoustic pressure and temperature is examined. Measurements by Farahi et al. (1990) indicate that the cross-sensitivity between temperature and axial strain may be significant for a polarization-maintaining fiber Fabry-Perot interferometer; however, no one has examined the significance of cross-sensitivity for the Mach-Zehnder case. Sensitivities to acoustic pressure and temperature, and the cross-sensitivity generated by simultaneous disturbances are determined both analytically and numerically. The fiber’s relatively high temperature sensitivity compared with its acoustic pressure sensitivity suggests that a short length of sensing fiber is sufficient for use as a temperature sensor with little or no interference from acoustic pressure. To measure acoustic pressure, however, a straight length of the fiber examined in this study is not sufficient. In practice, this sensing fiber could be coiled around a compliant cylinder or into a small diameter sensing element to enhance longitudinal strain and thus sensitivity. Results show that in either case, the cross-sensitivity is extremely small and can be ignored.

Simultaneous measurement of structural vibration and temperature using an embedded optical fiber in a flat plate composite structure

Numerical results from this study show that a single polarization‐maintaining optical fiber embedded in a composite flat plate is able to simultaneously measure low‐frequency structural vibration and temperature. Theoretical estimates of sensitivities for the optical fiber sensor are presented with consideration of the cross sensitivity caused by simultaneous disturbances. An analysis of the composite plate and fiber based on the theories of linear elasticity and photoelasticity is used to estimate sensitivities of the embedded fiber. A finite element analysis using ANSYS is used to determine the state of stress in the composite plate. Results of this study show that simultaneous changes in structural vibration and temperature can easily be resolved.

DYNAMICS AND CONTROL OF CROSS-FLOW GRAIN DRYERS 11. A FEEDFORWARD-FEEDBACK CONTROL STRATEGY

ABSTRACT A feedforward-feedback control of a cross-flow dryer is developed based on a simple mass balance on the dryer. The feedforward action is based on a pseudo inlet moisture and adjusts the grain flow to correct for inlet moisture variations. The feedback loop accounts for possible process changes and model inaccuracies. Simulations of a rice dryer show good control of the outlet moisture for variations in the inlet moisture with or without simultaneous disturbances in air flowrate. Effect of the'feedforward algorithm on feedback control is also investigated and the suggested combination of feedforward and feedback controls is tested for variations in the inlet moisture when its measurements are biased.

Feedforward-Feedback Control of a Cross-Flow Grain Dryer

A feedforward-feedback control of a cross-flow dryer is developed based on a simple mass balance on the dryer, rather than on indirect approaches and empirical relations. The feedforward action is based on a pseudo inlet moisture and adjusts the grain flow to correct for inlet moisture variations. A feedback loop is also added to account for possible process changes and model inaccuracies. Simulations of a rice dryer show good control of the outlet moisture for variations in the inlet moisture with or without simultaneous disturbances in air flowrate. Effect of the feedforward algorithm on feedback control is also investigated, and the suggested combination of feedforward and feedback controls is tested for variations in the inlet moisture when its measurements are biased.

Transcutaneous measurements of skin O2 supply and blood gases.

The data of the O2 exchange through the surface of the skin show that a part of the normal upper skin can be supplied with O2 from the surrounding atmosphere. This may be important in pathological situations although probably simultaneous disturbances of the substrate supply may be more serious. The noninvasive continuous registration of skin surface pO2 (and pCO2) allows to monitor skin oxygen supply under different conditions. The new optical sensing of pssO2 and of the local O2 flux into the skin opens up new promising possibilities for quantification of the skin oxygen supply.

Does the timing of aneurysm surgery neglect the real problems of subarachnoid haemorrhage?

In 1984, in connection with the introduction of the calcium antagonist nimodipine, a new strategy for the treatment of subarachnoid haemorrhage (SAH) due to ruptured aneurysm was developed in our hospital. With no rigid regard to "timing" all patients undergo surgery as soon as possible. The only exception being those in Hunt and Hess grades IV and V without space-occupying intracranial haemorrhage and those bearing aneurysms of the vertebrobasilar circulation that are difficult of access. As soon as the risk of rebleeding has been eliminated surgically an active therapy against the possible consequences of SAH--cerebral vasospasm and simultaneous disturbances of autoregulation--is started. It consists in lowering the increased intracranial pressure, raising of mean arterial pressure and improving of rheological properties of the blood in order to prevent delayed build-up of neurological deficit due to ischaemia. It goes without saying that calcium antagonists are given from the very beginning of the patient's treatment even before operation. The advantages of this therapeutic concept are demonstrated by two series of non-selected consecutive patient material. The first series (A; n = 135) was treated between 1981 and 1984 before the change in treatment strategy, the second (B; n = 183) from 1984 to 1986 after that change. The overall mortality in series A was 27%, that in series B 20%. Operative mortality could be reduced from 22% to 16% in patients having undergone early operation and from 6% to 2% in patients with late surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Phosphatidylethanolamine methyltransferase and cAMP, cGMP phosphodiesterases in lymphocytes and monocytes in sarcoidosis

Among the various hypotheses proposed to explain immune cell defect in sarcoidosis, we examined thoroughly that of Faguet who described abnormalities of signal transmission at lymphocyte membrane level. Phosphatidylethanolamine methyltransferase and cAMP cGMP phosphodiesterases were studied in blood lymphocytes and monocytes from 8 subjects with sarcoidosis disease. Phosphatidylethanolamine methyltransferase (PMT 1) plays an important regulatory role in membrane signal transmission. cAMP and cGMP phosphodiesterases (PDE) regulate cytoplasmic cyclic nucleotide levels and so participate in the modulation of the cell cycle. We observed a decreased PMT 1 activity in lymphocytes and monocytes and a decreased cAMP and cGMP PDE activities in monocytes. It is not now possible to say if these abnormalities are primary or secondary. Whatever the origin of this dysfunctioning, these results evoke simultaneous disturbances of membrane signal transmission and cell cycle in monocytes and membrane abnormalities in lymphocytes. These abnormalities could explain some immune cell defects in sarcoidosis disease.

Large simultaneous disturbances (LSDs) in the Antarctic ionosphere

A high frequency radio Doppler experiment was deployed in the Antarctic Peninsula region, centred on Argentine Islands (65°15′S, 64°16′W; L = 2.3), to investigate the morphology and sources of ionospheric disturbances. The experiment consisted of a three-transmitter dual frequency network which permits horizontal and vertical propagation velocities to be estimated over a north-south baseline of 200 km and an east-west baseline of 100 km. A new class of ionospheric disturbance has been observed, in the period range 10 min−1 h. These disturbances are characterised by unusually good correlation between perturbations on all available Doppler signals, but are apparently non—propagating and occur simultaneously at each reflection point. Several of these events display large (2 Hz at about 5 MHz transmitted frequency) Doppler shifts, thus we have labelled them Large Simultaneous Disturbances (LSD s). Criteria for identification of LSD s are established and the analysis of one event is described in detail. The occurrence statistics of the LSD s are presented, including their seasonal and diurnal distributions. There is no clear general relationship between LSD s and local geomagnetic field perturbations. However, examination of the magnetic indices AE and I RC indicates that there is a loose association between the occurrence and amplitude of LSD s and magnetic activity. Several possible mechanisms for the generation of LSD s at middle latitudes are reviewed. The most likely explanation is that high latitude electric fields penetrate to magnetic middle latitudes and drive the ionospheric plasma via the E × B drift.

The relationship between intracranial pressure, disturbances of brain function and prognosis

Long term measurements of the ventricular CSF pressure were made in 236 patients, before and after brain operations or trauma. Neither a definite rise in daily average pressure, nor the daily maximum values proved of any value in determining the prognosis when considered on their own. However, an analysis of the V F P over the course of several days, in relation to the simultaneous disturbances of neurological function, and particularly level of consciousness and brain metabolism (as shown by the CSF lactate levels), gives a much clearer indication as regards the prognosis. Thus, no patient survived when, after the fourth post-operative/post-traumatic day, there still persisted an average daily rise of V F P over 20 mm Hg which was associated with coma and a CSF lactate level of over 2.0 mmol/l.

Optimization of Linear Vehicle Suspensions Subjected to Simultaneous Guideway and External Force Disturbances

The optimum linear suspension for a vehicle traveling over a guideway with random irregularities and subjected to random external force disturbances is derived. The optimization is based upon a performance index which weights mean square vehicle acceleration (a measure of passenger comfort) and mean square relative displacement between the vehicle and guideway (a measure of required suspension dynamic excursion). The form of the optimum suspension is not restricted to a specific mechanical, magnetic or fluid suspension configuration. Performance curves and numerical design examples are presented to illustrate the influence of both guideway and external force disturbances upon optimum suspension performance capability.

DIABETES INSIPIDUS – THE COMPLEXITY OF THE SYNDROME

ABSTRACT It is suggested that in diabetes insipidus the possibility should be entertained of simultaneous disturbances in several of the systems concerned with water conservation. Criteria for the analysis of the syndrome are redefined. To illustrate the complexity of the syndrome, five cases are reported in the dog, among the first thus defined to be extensively investigated in any species both in life and at necropsy. In one, the syndrome was ascribed primarily to hypothalamo-neurohypophysial inadequacy associated with inflammatory atrophy of the secretory system, and in the second primarily to vasopressin resistance associated with renal medullary fibrosis. In three cases, the response to exogenous and endogenous vasopressin was inconsistent with a primary neurohypophysial or renal abnormality. In all, there was evidence of a hepatic dysfunction, recovery from which in one case was associated with a remission of the diabetic symptoms. Of a number of possible contributory factors, including vasopressin-resistance, primary polydipsia and excessive vasopressin inactivation, the last seemed probably the most important.

FAMILIAL PANMYELOPHTHISIS: FANCONI SYNDROME IN ADULTS

AbstractAn account is given of a similar and hitherto unknown clinical-hematologic syndrome in two adult brothers with marked hemorrhagic diathesis, diffuse pigmentation of the skin, violent pain in the bones and panhemocytopenia. In the younger brother, there is also a certain degree of infantilism. The elder brother died with all the symptoms of an intensive aplastic anemia; in the younger brother, the condition was stabilized after splenectomy. The blood picture in both patients was characterized by a hyperchromic anemia with remarkable micro- and macrocytosis, and an increased number of reticulocytes. In the younger brother, increased fragility of the red blood cells and an elevated serum iron content were observed. In both cases, an unusual increase of the plasmocytic and reticular cells and of the tissue mast cells was noticed in the bone marrow and, in the final stages of the disease, the marrow showed marked fibrosis.The disease is believed to be a variety, in adults, of the syndrome first described by Fanconi as a constitutional panmyelopathy occurring in children. The illness is the result of a hereditary pathologic reaction of the reticulo-histiocytic system and seems to have been caused by an anaphylactic-allergic phenomenon. The possibility is discussed that genetic connections may exist between this condition and other diseases, such as certain osteoscleroses and Cooley's anemia, which are characterized by simultaneous disturbances of the bone and bone marrow and by a similar blood morphology.

A soalr eruption of November 27, 1936, and simultaneous disturbances in Earth's magnetism, earth‐currents, and the ionospheric regions

Spectrohelioscope‐observations—From 16h 50m to 16h 58m GMT on November 27, 1936, an extremely bright circular flocculus was observed. Its approximate position was 6° South and 21° East.Magnetic record—A sudden commencement occurred in all three elements at 16h 50mGMT, terminating at 17h 00m after very small changes. These changes would hardly be worthy of note but for their simultaneity with a solar eruption.

A conspicuous solar eruption on April 8, 1936, and simultaneous disturbances on magnetic, ionospheric, and Earth‐current records at Huancayo Magnetic Observatory

During observations with the spectrohelioscope at the Huancayo Magnetic Observatory April 8, 1936, there occurred the most spectacular sunspot‐eruption, from the viewpoint of extent and intensity, that had been witnessed over a period of a year of observing there.The usual second period of observation (in accordance with the program of Commission No. 11 of the International Astronomical Union as arranged at the Paris meeting held in 1935) began at 16h 30m G.M.T., and to within a minute or two of seeing the phenomena about to be described, nothing unusual had been noticed. At 16h 45m, activity was first noticed surrounding the largest sunspot of a group of about six, located at approximately 23° north and 10° west of the central meridian. This increased in brightness until 16h 47m, reaching intensity “2,” and soon after, activity was noticed about three other smaller sunspots in the group, although rather mild in comparison with the first‐mentioned activity. Around 16h 50m the flocculus about the largest sunspot appeared to slowly decrease in size, but retained its great brilliancy. Before disappearing, the flocculus about the largest sunspot assumed the shape of a quite perfect crucifix. By 17h 03m the flocculi about all of the sunspots had returned to their original appearance.

A Solar Eruption and Simultaneous Disturbances at Huancayo Magnetic Observatory

A Solar Eruption and Simultaneous Disturbances at Huancayo Magnetic Observatory

Simultaneous Atmospheric and Cable Disturbances

A description is given of tests made to determine whether there is a relation between the interference currents in submarine cables and the atmospheric interference in radio. Racorder and oscillograph photographs show the agreement in a large number of interference signals. Cable and antenna, therefore, are influenced similarly by the same interference processes.