Terminal Zone Research Articles

Study on project trajectory of air-to-ground missile with strapdown seeker under multi constraints

The air-to-ground missile with strapdown seeker may have the problems, including small field of view(FOV), limited overload, and fall angle constraint. To solve the above mentioned problem, a phased guidance scheme is proposed. In this scheme, the attack trajectory is divided into the following six stages, including glided stage, fall angle constraint stage, target acquisition and adjustment stage, terminal guidance stage and blind zone stage. The glided stage is designed to increase range, the terminal fall angle is attained ahead of time at fall angle constraint stage. The aim of target acquisition and adjustment stage is to adjust the missile attitude, so that the target will fall within the FOV of the seeker. It creates good condition to capture the target for strapdown seeker. In the terminal stage, the guidance law of proportional navigation and attitude track are used to fit the needs of FOV constraint and attack accuracy. The simulation result shows that the project trajectory can solve the application of attacking moving targets for air-to-ground missile with strapdown seeker under multi constraints.

Study of Radial Wall Jets from Ceiling Diffusers at Variable Air Volume

The knowledge of the air velocity distribution in the supply jets is essential when designing ventilation and air conditioning systems. In this study, we tested and analyzed the velocity distributions in the radial wall jets—these jets are commonly used in ventilated rooms. Tests included jets from two ceiling diffusers of different constructions, at three airflow rates. The mean air speed distributions were measured with a 16-channel hot-sphere anemometer both in the self-similarity zone and in the terminal zone. A specially developed method of converting the mean speed to mean velocity was used. The measurement results show that the spread coefficients of the jets from both diffusers were the same, but the positions of the virtual origin were different. Due to the friction of the jet with the ceiling and the transfer of momentum to the recirculating flows, the momentum flux in the self-similarity zone decreased by up to 50%. An improved method for calculating velocity distributions in radial wall jets was developed and validated. This method takes into account the decrease of momentum, non-zero position of the jet origin, and faster velocity decrease in the terminal zone. A reliable method of predicting air velocity distribution in radial wall jets (RWJs) from ceiling diffusers may allow to properly select the diffuser size, its location, and the range of flow rate changes. The design process for variable air volume systems can be facilitated.

A Deep Learning and Geospatial Data-Based Channel Estimation Technique for Hybrid Massive MIMO Systems

This paper presents a novel channel estimation technique for the multi-user massive multiple-input multiple-output (MU-mMIMO) systems using angular-based hybrid precoding (AB-HP). The proposed channel estimation technique generates group-wise channel state information (CSI) of user terminal (UT) zones in the service area by deep neural networks (DNN) and fuzzy c-Means (FCM) clustering. The slow time-varying CSI between the base station (BS) and feasible UT locations in the service area is calculated from the geospatial data by offline ray tracing and a DNN-based path estimation model associated with the 1-dimensional convolutional neural network (1D-CNN) and regression tree ensembles. Then, the UT-level CSI of all feasible locations is grouped into clusters by a proposed FCM clustering. Finally, the service area is divided into a number of non-overlapping UT zones. Each UT zone is characterized by a corresponding set of clusters named as UT-group CSI, which is utilized in the analog RF beamformer design of AB-HP to reduce the required large online CSI overhead in the MU-mMIMO systems. Then, the reduced-size online CSI is employed in the baseband (BB) precoder of AB-HP. Simulations are conducted in the indoor scenario at 28 GHz and tested in an AB-HP MU-mMIMO system with a uniform rectangular array (URA) having 16x16=256 antennas and 22 RF chains. Illustrative results indicate that 91.4% online CSI can be reduced by using the proposed offline channel estimation technique as compared to the conventional online channel sounding. The proposed DNN-based path estimation technique produces same amount of UT-level CSI with runtime reduced by 65.8% as compared to the computationally expensive ray tracing.

Assessment of sperm storage across different reproductive modes in the elasmobranch fishes

The oviducal gland is a specialised region of the elasmobranch oviduct that is thought to be a site of sperm storage, among other functions. The phenomenon of female sperm storage in elasmobranchs has implications for the understanding of their reproductive ecology and the management of exploited populations, but relatively little information exists on its taxonomic extent. In the present study, oviducal glands from 29 different species, of varying reproductive modes, from the northern Indian and North East Atlantic oceans were examined using light microscopy for the presence of sperm. The organisation of the gland into four fundamental zones; club, papillary, baffle and terminal, was conserved across all species, with slight variations in relative zone volume due to reproductive mode. Spermatozoa observed within the oviducal gland were not limited to a particular reproductive mode or maturity stage. Although spermatozoa were most commonly encountered in the terminal zone tubules, in some species they were also encountered elsewhere in the gland. The storage of sperm may be a vital reproductive strategy for many species and furthering our taxonomic understanding of which species employ this strategy will help to better inform fisheries managers and protect exploited low reproductive species.

Comparison of the effects of a Mitchell’s myotensive technique and the strain-shortening technique on passive axial rotation of the cervical spine

The goal of research in vivo study was to compare the effects on range of motion, neutral zone, stiffness and hysteresis of muscle energy technique (Mitchell) and an original approach of myotensive technique by strain shortening. Methods . 23 healthy volunteers aged 22±2 years old were recruited, without any pain of the cervical spine. Each subject has received a myotensive technique (MET or SS) on the restricted side. The ranges of motion and torque were measured before and after the osteopathic technique. The neutral zones, stiffness and hysteresis were determined and compared. Results . The MET showed significant differences on the range of motion, neutral zone stiffness, terminal zone stiffness and hysteresis. The SS technique showed significant differences in the neutral zone and the hysteresis. Conclusion. Our study suggests that the strain shortening technique has a positive effect on the viscoelastic properties of the tissues in cervical spine region.

Spatiotemporal Analysis of Vegetation Cover Change in a Large Ephemeral River: Multi-Sensor Fusion of Unmanned Aerial Vehicle (UAV) and Landsat Imagery

Ephemeral rivers in arid regions act as linear oases, where corridors of vegetation supported by accessible groundwater and intermittent surface flows provide biological refugia in water-limited landscapes. The ecological and hydrological dynamics of these systems are poorly understood compared to perennial systems and subject to wide variation over space and time. This study used imagery obtained from an unmanned aerial vehicle (UAV) to enhance satellite data, which were then used to quantify change in woody vegetation cover along the ephemeral Kuiseb River in the Namib Desert over a 35-year period. Ultra-high resolution UAV imagery collected in 2016 was used to derive a model of fractional vegetation cover from five spectral vegetation indices, calculated from a contemporaneous Landsat 8 Operational Land Imager (OLI) image. The Normalized Difference Vegetation Index (NDVI) provided the linear best-fit relationship for calculating fractional cover; the model derived from the two 2016 datasets was subsequently applied to 24 intercalibrated Landsat images to calculate fractional vegetation cover for the Kuiseb extending back to 1984. Overall vegetation cover increased by 33% between 1984 and 2019, with the most highly vegetated reach of the river exhibiting the greatest positive change. This reach corresponds with the terminal alluvial zone, where most flood deposition occurs. The spatial and temporal trends discovered highlight the need for long-term monitoring of ephemeral ecosystems and demonstrate the efficacy of a multi-sensor approach to time series analysis using a UAV platform.

Reproductive biology of the Rasptail skate Rostroraja velezi (Rajiformes: Rajidae).

The Rasptail skate Rostroraja velezi is commercially exploited in artisanal elasmobranch fisheries along the west coast of Baja California Sur, Mexico, but information on its life history is limited. This study aimed to investigate the reproductive biology of R. velezi. A total of 105 specimens were caught from April 2008 to May 2012, including the largest reported specimen with 121 cm total length, 96 cm disc width (DW ). Females attained larger sizes than males. Males and females presented functional gonads. There was an asymmetry in the testes of males, with the left testis being larger. Histological analysis of the reproductive biology of R. velezi was performed here for the first time. The presence of sperm storage in females and spermatogenic development beginning at the first stages of maturity in males was recorded. It was possible to identify the development of secretions in the club, baffle and terminal zone of the oviducal gland. DW at maturity, defined as the DW at which 50% of the population is mature, was estimated at 68-72 cm for females and 65.1 cm for males. Egg-bearing females caught in April and May presented one egg capsule per uterus. Furthermore, a description of the egg capsule of R. velezi is provided. Elucidating the reproductive cycle, the type of reproductive strategies, and the fecundity of R. velezi will allow us to understand the impact of fisheries on this species.

Combining Single Molecule Super-Resolution Imaging Techniques to Unravel the Nanoscale Organization of the Presynapse.

The fusion of synaptic vesicles with the plasma membrane underpins neurotransmission. A number of presynaptic proteins play a critical role in overcoming the energy barrier inherent to the fusion of the negatively charged vesicular and plasma membranes. Emerging concepts suggest that this process is hierarchical and dependent on rapid and transient reorganization of proteins in and out of small nanoclusters located in the active zones of nerve terminals. Examining the nanoscale organization of presynaptic molecules requires super-resolution microscopy to overcome the limits of conventional light microscopy. In this chapter, we describe three super-resolution techniques that allow for the examination of the nanoscale organization of proteins within live hippocampal nerve terminals. We used (1) single-particle tracking photoactivated localization microscopy (sptPALM) to resolve the mobility and clustering of syntaxin1A (STX1A), (2) universal Point Accumulation Imaging in Nanoscale Topography (uPAINT) to study the mobility of a pool of vesicular-associated membrane protein 2 (VAMP2) transiting on the plasma membrane, and (3) subdiffractional Tracking of Internalized Molecules (sdTIM) to track VAMP2-positive recycling synaptic vesicles in conjunction with Cholera Toxin subunit B (CTB), which has recently been shown to be trafficked retrogradely from the presynapse to the cell body via signaling endosomes.

Glycan expression as a tool for a deeper understanding of a reproductive gland in a skate of economic importance.

Atlantoraja platana is an oviparous skate endemic to the south-west Atlantic Ocean, and is one of the skate species most exploited by local industrial bottom trawl fisheries. Oviparous elasmobranchs encapsulate their eggs in complex egg cases produced by the oviductal gland (OG). This organ is exclusively present in these fishes and comprises four distinct zones: club, baffle, papillary and terminal. The relative size and structural complexity of these zones correlate with mode of reproduction. Glycans are known to play major roles in reproduction so their distribution in each zone of the OG could explain the functional multiplicity of the gland in skates, but this topic has not been previously investigated. In this study, morphological, histochemical and lectin-histochemical analysis revealed various novel aspects of A. platana's OG. The club, papillary and terminal zones positively stained for periodic acid Schiff's reagent (PAS) and Alcian Blue (AB), indicating the presence of neutral and acid mucopolysaccharides. However, the buffle zone was negative for PAS and AB stains, but was positive for all the lectins used. Each zone of the OG had a characteristic pattern of glycan expression. Finally, we confirmed the presence of sperm but not sperm storage. This is the first lectin-histochemical study of the OG in chondrichtyan fish and it has proven to be an important tool to understand some of the mechanisms of fertility and reproductive success in economic important species such as A. platana.

Analysis of Electrohysterographic Signal Propagation Direction during Uterine Contraction: the Application of Directed Information.

The potential of using the information of uterine contractions (UCs) derived from electrohysterogram (EHG) has been recognized in early detection of preterm delivery. A better understanding of the conduction property of EHG is clinically useful for developing advanced methods to achieve a reliable prediction of preterm delivery. In this paper, a method to analyze the destination of EHG propagation has been proposed via the estimation of directed information (DI) between each pair of neighboring channels with a novel propagation terminal zone (PTZ) identification algorithm. The proposed method was applied to experimental data from the Icelandic 16-electrode EHG database. The results demonstrated that for more than 81.8% participants, the PTZ was identified along the medial axis of uterus, among which more than half have their PTZ determined in the center between the uterine fundus and public symphysis, which indicated a great probability of propagation of EHG signals towards the center of uterus plane.Clinical relevance- This study makes a fundamental contribution for predicting preterm delivery, which can provide improvement in obstetric care towards pregnancy monitoring.

Lateral and longitudinal distribution of riparian vegetation along an ephemeral river in Namibia using remote sensing techniques

Ephemeral rivers are key features of desert ecosystems, providing shallow groundwater and occasional surface flow, but compared to perennial systems, the structure of riparian forests in ephemeral rivers and their interactions with the hydrologic regime are poorly understood. This study examines the distribution of riparian woody species in the ephemeral Kuiseb River in central Namibia. Unmanned aerial vehicle (UAV) and satellite imagery were used to examine the structure of the riparian forest across lateral and longitudinal gradients. Woody plant abundance peaked in the terminal alluvial zone, the reach of the river where floods typically run dry. The five dominant species exhibited similar spatial patterns at latitudinal and longitudinal scales. Faidherbia albida and Salvadora persica were found more proximal to the active channel and concentrated in the terminal alluvial zone. Acacia (Vachellia) erioloba, Euclea pseudebenus, and Tamarix usneoides were more evenly dispersed laterally across the riparian zone and along the river's longitudinal profile. These spatial patterns correspond to plant physiological properties of hydrological dependence and gradients of water availability and soil composition. The tight coupling of plant distributions with water availability highlights the need for long-term monitoring of ephemeral riparian vegetation in light of potential future changes to the global hydrologic regime.

KAJIAN PENERAPAN ZONA PENGENDALIAN LALU LINTAS PADA PELAKSANAAN PEKERJAAN JALAN

Road works are almost close with moving traffic and potentially causing traffic disruption, congestion, delay, frustration, and more can cause collisions that would injure or kill road users and road workers. In order to remain resilient, the road worker must apply the zone concept on road works. This study aims to evaluate the application of Safety Technical Guidance on Road Work Location conducted by PT. Citra Muda Noer Bersaudara on Road Reconstruction of Junction (Koto Baru) - Jambi Border segment. So do a direct observation of the road work zone implemented by the contractor and compare it with the applicability in the guide. The implementation of the road work zone carried out by the contractor on the work package under review still lacks. In the implementation, the lack of which always occurs in every job implementation is the absence of a termination zone in all types of work, the transition zone is only applied to asphalt work, the early warning zone is only applied to road concrete work, asphalt overlay work and road shoulder work. Speed survey results show that the implementation of road work zone applied by the contractor can reduce the speed of the vehicle.

Entry guidance with terminal approach angle constraint

Achieving a desired terminal approach angle is required by an advanced entry vehicle in missions of landing or defense penetration. An entry guidance method is developed to satisfy the terminal approach angle constraint as well as the conventional constraints. The guidance method consists of a lateral guidance logic based on multiple aiming points and a two-phase trajectory tracking law. The aiming points are selected from a reference ground track and used to determine bank reversals for the lateral guidance logic. With the aid of aiming points, the vehicle can reach the entry terminal in a desired direction. The two-phase trajectory tracking law, corresponding to a two-dimensional and a three-dimensional trajectory, are designed to cooperate with the lateral guidance logic. Numerical results show that the guidance method is capable of flying the vehicle to the terminal zone with various desired approach angles, and meanwhile, robust to typical entry dispersions. The advantage of the guidance strategy is also verified by comparisons.

Central Nervous System Involvement in Breath-Hold Diving

Diving accident in breath-hold (BH) divers (Ama) is a stroke-like neurological condition involving the brain. Ama divers are at a risk of ischemic brain injuries which are situated in watershed or terminal zones of cerebral arteries, and/or corticomedullary junctional area of cerebral arteries. The underlying mechanisms of brain damage in BH diving remains to be elucidated. After repetitive BH dives, nitrogen (N2) bubbles may be formed in the venous side of tissues and flow into the right atrium. N2 bubbles passing through the heart or the lungs is the most likely contributing factor. The pathophysiology of diving accident in BH diving is unclear, and more studies for stroke are needed to further elucidate its nature. (Received 29 July, 2019; Accepted 10 January, 2020; Published 1 May, 2020).

Experimental study and characterization of an ultrahigh-voltage Ni/4H–SiC junction barrier Schottky rectifier with near ideal performances

Abstract An ultra-high voltage SiC JBS (silicon carbide junction barrier Schottky) rectifier utilizing a novel area-efficient multi-zone gradient modulated field limiting ring (MGM-FLR) technique have been fabricated, measured, and analysed in this paper. Ni-Schottky metal with a high barrier height is used to achieve a better trade-off between the on-resistance and the breakdown voltage. MGM-FLR, which is implanted simultaneously with the P+ grids within the active area of the device, forms a similar variation of lateral doping to mitigate the electric field crowding caused by junction curvature effect and obtains a maximum blocking voltage with minimally sized edge termination area. The fabricated device is tested to obtain a specific on-resistance is 140 mΩ cm2 and a reverse breakdown voltage of 14 kV with the leakage current of 10 μA, which is quite close to the theoretical value of parallel plane junction calculated using the device parameter of drift region 100 μm and the concentration 5 × 1014 cm−3. The highest Baliga's figure-of-merit (BFOM) 5.6 GW/cm2 was obtained for the proposed devices. Furthermore, the distribution of the extracted barrier height versus ideality factor on the wafer are demonstrated using I–V method. Impacts of ring spacing and zone of MGM-FLR termination on SiC device reverse blocking performance are also investigated in detail.

The Proteome of the Dentate Terminal Zone of the Perforant Path Indicates Presynaptic Impairment in Alzheimer Disease.

Synaptic dysfunction is an early pathogenic event in Alzheimer disease (AD) that contributes to network disturbances and cognitive decline. Some synapses are more vulnerable than others, including the synapses of the perforant path, which provides the main excitatory input to the hippocampus. To elucidate the molecular mechanisms underlying the dysfunction of these synapses, we performed an explorative proteomic study of the dentate terminal zone of the perforant path. The outer two-thirds of the molecular layer of the dentate gyrus, where the perforant path synapses are located, was microdissected from five subjects with AD and five controls. The microdissected tissues were dissolved and digested by trypsin. Peptides from each sample were labeled with different isobaric tags, pooled together and pre-fractionated into 72 fractions by high-resolution isoelectric focusing. Each fraction was then analyzed by liquid chromatography-mass spectrometry. We quantified the relative expression levels of 7322 proteins, whereof 724 showed significantly altered levels in AD. Our comprehensive data analysis using enrichment and pathway analyses strongly indicated that presynaptic signaling, such as exocytosis and synaptic vesicle cycle processes, is severely disturbed in this area in AD, whereas postsynaptic proteins remained unchanged. Among the significantly altered proteins, we selected three of the most downregulated synaptic proteins; complexin-1, complexin-2 and synaptogyrin-1, for further validation, using a new cohort consisting of six AD and eight control cases. Semi-quantitative analysis of immunohistochemical staining confirmed decreased levels of complexin-1, complexin-2 and synaptogyrin-1 in the outer two-thirds of the molecular layer of the dentate gyrus in AD. Our in-depth proteomic analysis provides extensive knowledge on the potential molecular mechanism underlying synaptic dysfunction related to AD and supports that presynaptic alterations are more important than postsynaptic changes in early stages of the disease. The specific synaptic proteins identified could potentially be targeted to halt synaptic dysfunction in AD.

Electrostatic dust transport on the terminator of atmosphereless bodies

Small dust particles may levitate over the surface of atmosphereless bodies, but to study electrostatic dust transport during a complete rotational period it is necessary to evaluate the surface potential at the terminator zone. We simulate the photo-electron layer and the dust charging process according to previously used models for dust levitation, but we propose a modification of the models to add the effects produced by surface roughness for low solar elevation angles. The correction for surface roughness on the model showed that a positive value for the surface potential and the electric field appear at the terminator. We found that submicron particles could be in stable levitation for small gravity fields. Our results also showed that the finest regolith grains can be lost into space due to the electrostatic repulsion.

Synthesis and characterization of novel functionalized perarylated polysiloxane for proton exchange membrane fuel cells

ABSTRACTThis work presents the synthesis and characterization of a pearylated polysiloxane material (PAP) from a polycondensation reaction, followed by functionalization with HClSO3 by an electrophilic substitution reaction. According to the characterization techniques applied, a sulfonated pearylated polysiloxane was also obtained, (SPAP). The purpose of this sulfonated material is to obtain an ionomer able to be applied in hydrogen fuel cells of the proton exchange membrane kind (PEMFC). The reaction to produce the polysiloxane precursor was carried out with the commercial reagents: PhSiCl3, Ph2SiCl2 and Ph3SiCl in anhydrous THF at 75 °C and the SPAP material was obtained by sulfonation of the precursor with chlorosulfonic acid. PAP and SPAP were characterized by 1H, NMR for liquids, 29Si NMR for solids, IR-ATR, SEM, and cyclic voltammetry. The NMR 29Si spectra show that PAP and PAPS contain crosslinking regions due to PhSiCl3, growing chain zones due to Ph2SiCl2 and polymer termination zones due to Ph3SiCl, obtaining a mixture of siloxanes. The analysis by cyclic voltammetry indicates that by integrating the area under the curve of the adsorption peaks of H2, a value of 0.062 mC/cm2 is obtained, a value close to the commercial ionomer of Nafion®.

The structure and operation of selected airports in Poland

Selected elements of the air transport infrastructure have been dis-cussed in the article. Basic zones of airports and terminals have been characterised. The article also explains why identification of airports is important and how these types of structures can be classified. An analysis of transport services delivered in 2016-2017 at Polish airports was conducted, the most important airports, as for the number of passengers served in our country, were mentioned as well as the most popular carriers providing the transport of people by means of airplanes were presented.

Correction to: Morphological diversity and connectivity of hippocampal interneurons.

The original version of this article inadvertently presented a mistake regarding the termination zones of entorhinal cotex in the dentate gyrus. The termination zones were erroneously swapped in both Figure 7. and the associated text.