MEASURES TO ENSURE THE SAFETY AND OPERATIONAL RELIABILITY OF THE FUNCTIONING OF IRRIGATION AND DRAINAGE SYSTEMS WITH A LONG SERVICE LIFE

The issues of ensuring the safety and operational reliability of the functioning of irrigation and drainage systems with a long service life are considered. It has been established that the service life of irrigation and drainage systems in the south of Russia is about 40-50 years, the average wear is 72%. In the Krasnodar territory the rate of wear of reservoirs, ponds and canals is about 80-100% which indicates to a signifi cant siltation and loss of throughput capacity. Depreciation of dams and dikes is 35-40%. The main damages of the HTS are erosion of the upper slope, malfunction of the spillway and silting of the reservoir bowl (pond) which leads to increased filtration through the dam body, an increase in the level of the depression curve and complication of the passage of fl ood water. Changes in the rules for the operation of hydraulic structures, in particular, a decrease in the normal retaining level in comparison with the design level is not a rare occurrence. At the same time, the HTS operation in the sparing mode can be considered a temporary measure used until repair or reconstruction is carried out. The operational efficiency of hydraulic structures with a high degree of wear at the level of ultimate loads and impacts below the design values is noticeably getting reduced. The use of constant monitoring, as well as forecasting the reliability of hydraulic structures, can reduce the severity of the problem. Safe and effi cient operation of hydraulic structures with a high degree of wear during the period preceding repair or reconstruction can be ensured by introducing a system for automated monitoring of hydraulic structures in combination with a decision support system (DSS).

Calculation of filtration process in channels

This article provides an analysis and recommendations of the factors that lead to the loss of water as a result of filtration in uncoated canals, rising groundwater levels, deterioration of land reclamation, reduction of canal efficiency coefficient. According to the project data, the part of the Greater Fergana canal from PK-930 to PK-1500 + 10 was built in the type of semi-excavated and natural canal. From PK-930 to PK-1040, the ground level is almost equal to the bottom water level, and the volume of soil discharged in this part of the canal is greater than in other parts. The canal is in the form of a trapezoid and has now changed its shape slightly as a result of a small amount of sedimentation and erosion. In uncoated canals and irrigation systems, there are a number of connections to perform the basic filtration calculation. These bonds are obtained according to Darcy’s law, filtration for homogeneous and isotropic soils. Using the available data, it is possible to determine the depression curve in canals and irrigation systems for all cases, the points that form its curvature, and the filtration rate that occurs in it. It consists of determining the filtration rate (q) of the system at a length of 1 pogm and the filtration coefficient (k) of the soil.

Filtration Bypassing Retaining Hydraulic Structures

Concrete dams that are part of river waterworks are integrated with earthworks or with banks using coastal abutments. If the soil of cost or earthen dam is permeable, then in the zone of contiguity water filtration occurs around the coastal abutment. Calculation of filtration bypassing the coastal abutment at specified water levels in the upper and lower pools is performed with the aim of constructing an encircling curve of depression and determining a gradient of filtration flow that controls the filtration strength of the soil beyond the abutment. This problem has no theoretical solutions – in view of its complexity, approximate calculation methods have been developed for individual calculation schemes. For the case when the soil behind the coastal abutment is homogeneous and isotropic, groundwater inflow from the coast is absent or insignificant and can be neglected, and the coastal abutment is located on a water bed and approximate methods by V. P. Nedrigi and R. R. Chugaeva are proposed in the paper. The experience of surveying a number of Belarusian hydropower stations has shown that the absence of a justified prediction pertaining to the position of groundwater levels beyond the estuary leads to a decrease in the strength and stability of the coastal abutment and its possible destruction. An experimental verification of the approximate method for calculation filtration bypassing the coastal abutment developed by R. R. Chugaev has been carried out in laboratory conditions. According to the obtained experience a depression curve encircling the abutment has been constructed which show good agreement between experimental and calculated data that allows to use this method for reasonable design of coastal abutment structures ensuring their reliable operation.

Relationship of the Reserve Vesicle Population to Synaptic Depression in the Tergotrochanteral and Dorsal Longitudinal Muscles of Drosophila

We have previously demonstrated that Drosophila synapses possess two vesicle populations—a small active zone population replenished by “fast” recycling and a much larger reserve population replenished by a slower recycling mechanism that includes endosomal intermediates. In this paper, we demonstrate that the synapses onto the tergotrochanteral muscle (TTM) are very unusual in that they possess only the active zone vesicle population but not the reserve population. The depression characteristics to repetitive stimulation of the TTM were compared with those of the dorsal longitudinal muscle (DLM), the synapses of which possess both an active zone and a reserve population. It was observed that the TTM response depressed more quickly than that of the DLM. To further explore the possible contribution of the reserve population to release, using the shibire mutant, DLM synapses were experimentally constructed that possess only the active zone population, and their depression characteristics were compared with those of the same synapses possessing both populations. It was observed that responses from DLM synapses possessing only the active zone population depressed more quickly than the same synapses possessing both populations. These experiments were conducted under conditions of blocked recycling so that the difference in stimulation tolerance represents the contribution of the reserve population to release. Furthermore, the depression curve of the DLM synapses lacking a reserve population now closely approximated that of the TTM synapses. These data suggest that the reserve vesicle population of DLM synapses may contribute to transmitter release during repetitive firing at physiological frequencies (5–10 Hz).

Spike-Timing-Dependent Plasticity and Relevant Mutual Information Maximization

Synaptic plasticity was recently shown to depend on the relative timing of the pre- and postsynaptic spikes. This article analytically derives a spike-dependent learning rule based on the principle of information maximization for a single neuron with spiking inputs. This rule is then transformed into a biologically feasible rule, which is compared to the experimentally observed plasticity. This comparison reveals that the biological rule increases information to a near-optimal level and provides insights into the structure of biological plasticity. It shows that the time dependency of synaptic potentiation should be determined by the synaptic transfer function and membrane leak. Potentiation consists of weight-dependent and weight-independent components whose weights are of the same order of magnitude. It further suggests that synaptic depression should be triggered by rare and relevant inputs but at the same time serves to unlearn the baseline statistics of the network's inputs. The optimal depression curve is uniformly extended in time, but biological constraints that cause the cell to forget past events may lead to a different shape, which is not specified by our current model. The structure of the optimal rule thus suggests a computational account for several temporal characteristics of the biological spike-timing-dependent rules.

A regression analytical approach to estimate the onset of activity of antidepressants

SummaryThe onset of activity of antidepressants is a clinically and theoretically important criterion of efficacy. We estimated the onset of activity by an intraindividual regression analytical approach. It is assumed that efficient treatment causes a fast shift of depression scores from a baseline level to an end level. From this assumption follows a limited number of opportunities for the onset of activity to occur. These opportunities correspond to different regression models which are estimated for each patient's depression course. The day of onset is concluded from the regression model which produces the best fit to the empirical depression curve. Results of a double-blind clinical trial comparing mianserin and amitriptyline are reported (n = 28). The methodological approach confirms that observer ratings by physicists show a significantly earlier onset of activity than self ratings by the patients. The D-S also shows a significantly earlier onset of activity of mianserin compared to amitriptyline. The discussion emphasises methodological aspects.