Improving the Dynamic Properties of a Medium-Speed Diesel Engine Using Variable Turbocharging

The article presents the results of a computational study of the possibilities of improving the dynamic properties of diesel engines by using a controlled turbocharger. A promising medium-speed diesel engine 12 ChN 26.5 / 31, operating in ship conditions was researched. A mathematical model has been developed for a combined engine as a part of a complex adaptive control system with channels for regulating the speed of rotation and turbocharging. The computer model was implemented in the MATLAB / Simulink software package. Calculated transient processes of the working process parameters of a diesel engine were considered for two methods of turbocharging control: multistage turbocharging and variable geometry turbines – turbines with a variable position of the guide vanes. The effect of pneumatic correction of the fuel supply on the dynamic characteristics of the engine under consideration was studied. The obtained results were analyzed. A comparison of various options for regulating the air supply system in terms of the efficiency of improving the dynamic properties of diesel engines was performed.

Influence of the position and energy of local rapid heating of the supersonic gas flow on the position of the separation point on the surface of airfoil

Using numerical simulation, the study of the process of rapid local energy release in supersonic flow in a two-dimensional unsteady case and the process of separation point shift by a gas-dynamic perturbation caused by the energy input into the flow were carried out. The flow around the airfoil was modeled as laminar, and local heat release as a instantaneous isochoric process without changing the gas density. The value of energy input and the place of gas heating on the surface of the airfoil were varied. The cases of initiation of energy input at a certain distance before and after the initial position of the separation point, as well as immediately before the separation point, were considered. During obtained flow patterns processing, the displacement of the separation point position downstream, the time of this displacement, the position and size of the separation region with reattachment and the lifetime of this flow zone were determined. The obtained data can help to choose a strategy for initiating energy input in a repetitively pulsed regime, as well as in a regime of a variable position of energy release on the surface of a body, streamlined by compressible gas flow.

LSTM-DDPG for Trading with Variable Positions

In recent years, machine learning for trading has been widely studied. The direction and size of position should be determined in trading decisions based on market conditions. However, there is no research so far that considers variable position sizes in models developed for trading purposes. In this paper, we propose a deep reinforcement learning model named LSTM-DDPG to make trading decisions with variable positions. Specifically, we consider the trading process as a Partially Observable Markov Decision Process, in which the long short-term memory (LSTM) network is used to extract market state features and the deep deterministic policy gradient (DDPG) framework is used to make trading decisions concerning the direction and variable size of position. We test the LSTM-DDPG model on IF300 (index futures of China stock market) data and the results show that LSTM-DDPG with variable positions performs better in terms of return and risk than models with fixed or few-level positions. In addition, the investment potential of the model can be better tapped by the reward function of the differential Sharpe ratio than that of profit reward function.

Clause Structure and Word Order in Ákè

Ákè is by historical and linguistic facts a dialect of Edo which has not received significant linguistic attention. This neglect informs an inquiry into the in ternal structure and organization of its basic clause. This paper studies data of everyday usage of competent speakers of Ákè and argues that it displays a subject-verb-object order. The study provides a not too elaborate description of the nominal and verbal constructions in Ákè and reduces the description to analysis using the X-bar theory as conceived within the Minimalist Program. It therefore states that nominal phrases can be analysed as a projection of Determiner Phrase (DP) because independent existence is not a requirement for considering an element as the head of a projection. The variable position which the head D occupies in the superficial syntax of Ákè is analysed as the effect of movement for feature checking. In the spirit of the Minimalist Program, this study recognizes the head of the clause as Tense (T), which could be overt or null and predicts that it dominates Negative Phrase (NegP) as Neg is assumed to c-select the Verb Phrase (VP).

Identification of the Effect of Ultrasonic Friction Reduction in Metal-Elastomer Contacts Using a Two-Control-Loop Tribometer

Pneumatic cylinders are widely used in highly dynamic processes, such as handling and conveying tasks. They must work both reliably and accurately. The positioning accuracy suffers from the stick-slip effect due to strong adhesive forces during the seal contact and the associated high breakaway forces. To achieve smooth motion of the piston rod and increased position accuracy despite highly variable position dynamics, sliding friction and breakaway force must be reduced. This contribution presents a specially designed linear tribometer that has two types of control. Velocity control allows the investigation of sliding friction mechanisms. Friction force control allows investigation of the breakaway force. Due to its bearing type, the nearly disturbance-free detection of stick-slip transients and the dynamic contact behavior of the sliding friction force was possible. The reduction of the friction force was achieved by a superposition of the piston rod’s movement by longitudinal ultrasonic vibrations. This led to significant reductions in friction forces at the rubber/metal interface. In addition, the effects of ultrasonic frequency and vibration amplitude on the friction reduction were investigated. With regard to the breakaway force, significant success was achieved by the excitation. The force control made it possible to identify the characteristic movement of the sealing ring during a breakaway process.

A novel external beam radiotherapy method for cervical cancer patients using virtual straight or bending boost areas; an in-silico feasibility study

Aim To investigate the potential role of a novel spatially fractionated radiation therapy (SFRT) method where heterogeneous dose patterns are created in target areas with virtual rods, straight or curving, of variable position, diameter, separation and alignment personalised to a patient’s anatomy. The images chosen for this study were CT scans acquired for the external beam part of radiotherapy. Methods Ten patients with locally advanced cervical cancer were retrospectively investigated with SFRT. The dose prescription was 30 Gy in 5 fractions to 90% target volume coverage. Peak-and-valley (SFRT_1) and peak-only (SFRT_2) strategies were applied to generate the heterogeneous dose distributions. The planning objectives for the target (CTV) were D90% ≥ 30 Gy, V45Gy ≥ 50–55% and V60Gy ≥ 30%. The planning objectives for the organs at risk (OAR) were: D2cm3 ≤ 23.75 Gy, 17.0 Gy, 19.5 Gy, 17.0 Gy for the bladder, rectum, sigmoid and bowel, respectively. The plan comparison was performed employing the quantitative analysis of the dose-volume histograms. Results The D2cm3 was 22.4 ± 2.0 (22.6 ± 2.1) and 13.9 ± 2.9 (13.2 ± 3.0) for the bladder and the rectum for SFRT_1 (SFRT_2). The results for the sigmoid and the bowel were 2.6 ± 3.1 (2.8 ± 3.0) and 9.1 ± 5.9 (9.7 ± 7.3), respectively. The hotspots in the target volume were V45Gy = 43.1 ± 7.5% (56.6 ± 5.6%) and V60Gy = 15.4 ± 5.6% (26.8 ± 6.6%) for SFRT_1 (SFRT_2). To account for potential uncertainties in the positioning, the dose prescription could be escalated to D90% = 33–35 Gy to the CTV without compromising any constraints to the OARs Conclusion In this dosimetric study, the proposed novel planning technique for boosting the cervix uteri was associated with high-quality plans, respecting constraints for the organs at risk and approaching the level of dose heterogeneity achieved with routine brachytherapy. Based on a sample of 10 patients, the results are promising and might lead to a phase I clinical trial.

The Institutional Impacts of Algorithmic Distribution: Facebook and the Australian News Media

Since changing its algorithm in January 2018 to boost the content of family and friends over other content (including news), Facebook has signaled that it is less interested in news. However, the field is still trying to understand the long-term impacts of this change for news publishers. This is a problem because policymakers and legislators across the world are becoming concerned about the relationship between platforms and publishers. In particular, there are worries that platforms’ ability to make unilateral decisions about how their algorithms operate may harm the economic sustainability of journalism. This article provides some clarity around the relationship between these two parties through a longitudinal study of the Australian news media sector’s relationship with Facebook from 2014 to 2020, with a particular focus on the January 2018 algorithm change. We do this by analyzing Facebook data (2,082,804 posts from CrowdTangle) and external traffic data from 32 major Australian news outlets. These data are contextualized by additional desk research. We identify a range of trends including the decline of news sharing, the collapse in the performance of “social news,” the variable position of social media as a source of referral traffic, and, most critically, the diffused nature of the 2018 algorithm change. Our approach cannot make direct causal inferences. We can only identify trends in on-platform performance and referral traffic, which we then contextualize with industry reportage. However, the data provide vital longitudinal insights into the performance and responses of individual media outlets, news categories, and the Australian media sector as a whole during a critical moment of algorithmic change.

Positioning Practices of Orientation and Mobility Specialists When Teaching Street Crossings: Is There a Standard Approach?

Introduction: An important skill for orientation and mobility (O&M) specialists to have is to monitor clients appropriately when they are learning to cross intersections. Techniques books provide some suggestions for positioning during street crossings, but no research has been conducted about consensus or priorities for making appropriate decisions on positioning. The purpose of this study was to investigate general positioning decisions using visual monitoring techniques. Method: A total of 234 participants (practicing O&M specialists, preservice O&M students, and O&M university personnel) completed a 40-question survey. The survey included demographic questions, diagrams of intersections that participants used to select positioning locations, questions about lanes of threat, and questions about important factors to consider when positioning to monitor safety. Commonality of selections were analyzed and compared with demographic information. Results: The greatest consensus was found for all intersection types when the client is positioned on the corner waiting to cross and for identification of the first lane of threat. More variable position selections were made for monitoring during the crossings, and the second and third lane of threat selections were also more variable. Factors respondents indicated as most important to consider when positioning aligned with their positioning choices overall. Discussion: Personnel preparation programs may want to consider to what extent they teach considerations for positioning before and during crossings, and whether the predominant tendency to put oneself between the client and traffic warrants additional conversation. Future research should look at more complex intersections and the additional nuances used to make positioning choices. Implications for practitioners: Practitioners should reflect on whether they actively change their positioning decisions based on the situation and type of intersection versus tending to use a standard strategy.

Genetic variability of SARS-CoV-2 in biological samples from patients in Moscow

Currently, a lot of attention is given to SARS-CoV-2 subpopulations and their coexistence with different genomic variants within the same patient. In this study, we performed next-generation whole-genome sequencing and assembly of viruses from samples representing swabs or autopsy specimens obtained from patients diagnosed with СOVID-19, which were initially confirmed by the real-time polymerase chain reaction (Ct = 10.4–19.8). Samples were prepared for sequencing by using the SCV-2000bp protocol. The obtained data were checked for presence of more than one SARS-CoV-2 genetic variants in a sample. Variants of nucleotide substitutions, coverage for each variant, and location of the variable position in the reference genome were detected with tools incorporated in the CLC Genomics Workbench program. In our search for variable nucleotide positions, we assumed that the sample had two genetic variants (not more); the threshold value ≥ 90% was set for probability of the identified variant. Variants represented by less than 20% of the reads in the total coverage were not taken into consideration. The obtained results showed that 5 samples had variability, i.e. they had several genetic variants of SARS-CoV-2. In 4 samples, both of the detected genomic variants differed only in one nucleotide position. The fifth sample demonstrated more substantial differences: a total of 3 variable positions and one three-nucleotide deletion. Our study shows that different genetic variants of SARS-CoV-2 can coexist within the same patient.

The many bits of positional information

ABSTRACTHalf a century after Lewis Wolpert's seminal conceptual advance on how cellular fates distribute in space, we provide a brief historical perspective on how the concept of positional information emerged and influenced the field of developmental biology and beyond. We focus on a modern interpretation of this concept in terms of information theory, largely centered on its application to cell specification in the early Drosophila embryo. We argue that a true physical variable (position) is encoded in local concentrations of patterning molecules, that this mapping is stochastic, and that the processes by which positions and corresponding cell fates are determined based on these concentrations need to take such stochasticity into account. With this approach, we shift the focus from biological mechanisms, molecules, genes and pathways to quantitative systems-level questions: where does positional information reside, how it is transformed and accessed during development, and what fundamental limits it is subject to?