A Hydraulic Analysis of Shock Wave Generation Mechanism on Flat Spillway Chutes through Physical Modeling

Shock waves are generated downstream of spillways during flood operations, which have adverse effects on spillway operations. This paper presents the physical model study of shock waves at the Mohmand Dam Spillway project, Pakistan. In this study, hydraulic analysis of shock waves was carried out to investigate its generation mechanism. Different experiments were performed to analyze the rooster tail on a flat spillway chute and to examine the factors affecting the characteristics of the rooster tail. The study results show that shock wave height is influenced by spillway chute slope, pier shape, and flow depth. Moreover, the height of the shock wave can be minimized by installing a semi-elliptical pier on the tail part of the main pier. Further modifications in the geometry of the extended tail part of the pier are recommended for the elimination of the shock wave. Based on observed data collected from the model study, an empirical equation was developed to estimate the shock wave height generated on the flat slope spillway chutes (5° to 10°).

ПРОЕКТУВАННЯ СТУЛКОВОГО ВІДСІКУ ХВОСТОВИХ ВАНТАЖНИХ ЛЮКІВ ЛІТАКІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ

The method for determining the main parameters of the tail cargo doors of transport category aircraft is developed. There have been prepared initial data and described the methodology for finding them. An example based on an existing transport aircraft is considered. The basic nomenclature of transported cargoes of the designed aircraft, its dimensions and weight, methods of loading and mooring, additional loading equipment were taken as initial data. As well as such necessary design, operational and regulatory parameters and data as landing gear type, its “kneeling” system, rails of the upper loading equipment for loading and unloading, cargo trajectories during loading and landing, requirements of international regulatory organizations FAR, CS, AP. The principle of determining the dimensions of the cargo compartment, cargo floor and the hitting platforms in the form of ramp with pressure door, ladders is presented, based on the initial data. Taking into account the loading and unloading, landing operations described the dependence of the ramp length on the length of the cargo floor. The correct formation of these parameters is one of the most important tasks, from the solution of which directly depend the operational characteristics of the future transport aircraft. A method for designing cargo door fairings in the transport category aircraft fuselage tail part is also presented. There have been determined the main features of the fairings compartment, its main components and their varieties, depending on the scheme of the cargo door. At the stage of preliminary design, the principles for determining the main parameters of the fairings compartments based on their design purpose are outlined.Also provided information on the fairings compartment structural elements parameters selection: the axes of the fairings hinge, the selection of control cylinders and their installation, the parameters of the open and closed position locks, pressurization and sealing of the fairings compartment. Considered the design features of the fuselage tail section various theories fairings compartment - made in cross-section with one radius (in the shape of a cylinder) and given in cross-section with two radii (double-deck).

Quantile composite-based path modeling: algorithms, properties and applications

Composite-based path modeling aims to study the relationships among a set of constructs, that is a representation of theoretical concepts. Such constructs are operationalized as composites (i.e. linear combinations of observed or manifest variables). The traditional partial least squares approach to composite-based path modeling focuses on the conditional means of the response distributions, being based on ordinary least squares regressions. Several are the cases where limiting to the mean could not reveal interesting effects at other locations of the outcome variables. Among these: when response variables are highly skewed, distributions have heavy tails and the analysis is concerned also about the tail part, heteroscedastic variances of the errors is present, distributions are characterized by outliers and other extreme data. In such cases, the quantile approach to path modeling is a valuable tool to complement the traditional approach, analyzing the entire distribution of outcome variables. Previous research has already shown the benefits of Quantile Composite-based Path Modeling but the methodological properties of the method have never been investigated. This paper offers a complete description of Quantile Composite-based Path Modeling, illustrating in details the method, the algorithms, the partial optimization criteria along with the machinery for validating and assessing the models. The asymptotic properties of the method are investigated through a simulation study. Moreover, an application on chronic kidney disease in diabetic patients is used to provide guidelines for the interpretation of results and to show the potentialities of the method to detect heterogeneity in the variable relationships.

Temporal and spatial evolution of various functional neurons during demyelination induced by cuprizone

Multiple sclerosis (MS) is an inflammatory, demyelinating, and neurodegenerative disease of the central nervous system (CNS). Here, we reported the temporal and spatial evolution of various functional neurons during demyelination in a cuprizone (CPZ)-induced mouse model. CPZ did not significantly induce the damage of axons and neurons after 2 weeks of feeding. However, after 4-6 weeks of CPZ feeding, axons and neurons were markedly reduced in the cortex, posterior thalamic nuclear group, and hippocampus. Simultaneously, the expression of TPH+ tryptophan neurons and VGLUT1+ glutamate neurons was obviously decreased, and the expression of TH+ dopaminergic neurons was slightly decreased in the tail part of the substantia nigra striatum, while the number of ChAT+ cholinergic neurons was not significantly different in the brain. In the second week of feeding, CPZ caused a higher level of glutamate secretion and up-regulated the expression of EAAT2 on astrocytes, which should contribute to rapid and sufficient glutamate uptake and removal. This finding reveals that astrocyte-driven glutamate retake protected the CNS from excitotoxicity by rapid re-uptake of glutamate in 4-6 weeks of CPZ feeding. At this stage, although NG2+ oligodendroglia progenitor cells (OPCs) were enhanced in the demyelination foci, the myelin sheath was still absent. In conclusion, we comprehensively observed the temporal and spatial evolution of various functional neurons. Our results will assist with understanding how demyelination affects neurons during CPZ-induced demyelination and provides novel information for neuroprotection in myelin regeneration and demyelinating diseases.

A STUDY ON HUMAN CADAVERIC PANCREAS: VARIATIONS IN DIAMETERS OF ISLETS OF LANGERHANS IN DIFFERENT AGE GROUP

INTRODUCTION: The islets of Langerhans may contain a few cells or many hundreds of polygonal cells arranged in short irregular cords that are abundantly invested with a network of fenestrated capillaries to produce a hormone with glucose-lowering effect. MATERIALS AND METHODS: The descriptive and cross-sectional study was done in the Department of Anatomy, Forensic Medicine& Pathology of Gauhati Medical College, Guwahati based on collection of 103 human pancreas aging from 13 to 78 years of both sexes.The collected samples were divided into group A (10-19 years),B (20-29 years),C (30-39 years),D (40-49 years),E (50-59 years),F (60-69 years) and G (≥70 years).Measurement of five slides selected from head, body and tail region were examined under 400 magnification. RESULTS AND OBSERVATION:The differences between the diameter of pancreatic islets for head part were statistically significant in A vs B,A vs D,A vs E,A vs F,A vs G,B vs D,B vs E,B vs F,B vs G, C vs E,C vs F,C vs G,F vs G in body part A vs B,A vs C,A vs F, A vs G,B vs C,B vs D,B vs E,B vs F,B vs G,C vs G,D vs G,E vs G and F vs G.and in tail part between A vs B,A vs C,A vs D,A vs E, A vs F, A vs G, B vs C, B vs D, B vs E, B vs G, C vs E, C vs F, C vs G, D vs F, D vs G, E vs F , E vs G and F vs G region. CONCLUSIONS:In the 3 region it was found that in the both extremities of life the diameter of islets of Langerhans was gradually decreased as age increases. Larger samples and advanced procedures in case of normal and abnormal population like people with diabetes disease for further studies may recommended.

PolySimp: A Tool for Polygon Simplification Based on the Underlying Scaling Hierarchy

Map generalization is a process of reducing the contents of a map or data to properly show a geographic feature(s) at a smaller extent. Over the past few years, the fractal way of thinking has emerged as a new paradigm for map generalization. A geographic feature can be deemed as a fractal given the perspective of scaling, as its rough, irregular, and unsmooth shape inherently holds a striking scaling hierarchy of far more small elements than large ones. The pattern of far more small things than large ones is a de facto heavy tailed distribution. In this paper, we apply the scaling hierarchy for map generalization to polygonal features. To do this, we firstly revisit the scaling hierarchy of a classic fractal: the Koch Snowflake. We then review previous work that used the Douglas–Peuker algorithm, which identifies characteristic points on a line to derive three types of measures that are long-tailed distributed: the baseline length (d), the perpendicular distance to the baseline (x), and the area formed by x and d (area). More importantly, we extend the usage of the three measures to other most popular cartographical generalization methods; i.e., the bend simplify method, Visvalingam–Whyatt method, and hierarchical decomposition method, each of which decomposes any polygon into a set of bends, triangles, or convex hulls as basic geometric units for simplification. The different levels of details of the polygon can then be derived by recursively selecting the head part of geometric units and omitting the tail part using head/tail breaks, which is a new classification scheme for data with a heavy-tailed distribution. Since there are currently few tools with which to readily conduct the polygon simplification from such a fractal perspective, we have developed PolySimp, a tool that integrates the mentioned four algorithms for polygon simplification based on its underlying scaling hierarchy. The British coastline was selected to demonstrate the tool’s usefulness. The developed tool can be expected to showcase the applicability of fractal way of thinking and contribute to the development of map generalization.

Structural organization and cohesiveness of foraging groups in Camponotus sericeus (Fabricius) (Hymenoptera: Formicidae): locally regulated or self-organized?

Background In Camponotus sericeus (Fabricius), foraging ants are recruited mostly as individuals but occasionally as small groups that move in a single file. We studied the structure and organization of these small foraging groups and attempted to understand the process through which the cohesiveness of the moving file is maintained. Results The recruited group moves in a single file as if steered by a leader at the moving tip. Ants in the group were found to exhibit certain fidelity to their respective positions in the file, despite the occasional breakdown of the cohesiveness due to disturbance and or obstructions on their path. This fidelity decreases from both ends towards the middle part of the file. Accordingly, three segments could be recognized in the moving file: (a) the leading ant that almost always maintains its position and steers the group, (b) a short tail part with a few ants that always trail the file and, (c) the mid part that binds the group; ants in this segment always tend to follow the leader through a cascading chain of tactile communication. If the leader ant is removed, entire group loses its orientation and enters into a chaotic search state. But removing any other ant does not affect the cohesiveness; rather it’s position is occupied by the member preceding it and thus maintains the link in the group. Conclusions The cohesiveness of the moving group appeared to result from (a) regulation of the movement of the group by the leading ant, and, (b) an interactive process among the rest of the ants. Based on these two elements, a simple automated model of the group’s movement was developed that could effectively mimic the observed pattern. We also provide evidence to suggest that recruitment of groups occurs in the direction of, and in response to, the information received by the colony on, the resource rich patches.

Decoding Decentralized Control Mechanism Underlying Adaptive and Versatile Locomotion of Snakes

Snakes have no limbs and can move in various environments using a simple elongated limbless body structure obtained through a long-term evolutionary process. Specifically, snakes have various locomotion patterns, which they change in response to conditions encountered. For example, on an unstructured terrain, snakes actively utilize the terrain’s irregularities and move effectively by actively pushing their bodies against the “scaffolds” that they encounter. In a narrow aisle, snakes exhibit concertina locomotion, in which the tail part of the body is pulled forward with the head part anchored, and this is followed by the extension of the head part with the tail part anchored. Furthermore, snakes often exhibit three-dimensional (3-D) locomotion patterns wherein the points of ground contact change in a spatiotemporal manner, such as sidewinding and sinus-lifting locomotion. This ability is achieved possibly by a decentralized control mechanism, which is still mostly unknown. In this study, we address this aspect by employing a synthetic approach to understand locomotion mechanisms by developing mathematical models and robots. We propose a Tegotae-based decentralized control mechanism and use a 2-D snake-like robot to demonstrate that it can exhibit scaffold-based and concertina locomotion. Moreover, we extend the proposed mechanism to 3D and use a 3-D snake-like robot to demonstrate that it can exhibit sidewinding and sinus-lifting locomotion. We believe that our findings will form a basis for developing snake-like robots applicable to search-and-rescue operations as well as understanding the essential decentralized control mechanism underlying animal locomotion.