Research on Tool Presetting and Tool Deviation in CNC Lead Screw Grinding Process

In the process of tool presetting for an CNC lead screw grinding, when A-axis rotating and Z-axis shifting synchronously according to the screw pitch length, L, of the lead screw workpiece, the handwheel corresponding to X-axis and Z-axis, respectively, is operated to align the grinding wheel with the middle of the screw groove. Then, the coordinates of Z-axis, A-axis and X-axis of the current position are recorded, and the coordinates of the grinding start position and grinding end position of the lead screw workpiece are calculated accordingly.However, due to the mutual following error of Z-axis and A-axis in the synchronous movement process, tool deviation typically occurs when the grinding wheel moves from the grinding start position to the grinding end position to grind the lead screw workpiece. More specifically, the grinding wheel slightly deviates from the middle of the screw groove to the left or right of the screw groove.To offset this deviation, the root cause for creating the deviation is analyzed, and a method to correct the tool deviation is proposed: First, the CNC system sends out grinding instructions, according to the requirements of grinding process, to make the A-axis and the Z-axis move synchronously. In the meantime, the CNC system measures and records the current coordinates of A-axis and Z-axis, and calculates the tool deviation caused by the mutual following error between Z-axis and A-axis. As a result the grinding start position and the grinding end position are adjusted in light of the value of tool deviation in the subsequent grinding process, so as to address the tool deviation issue.

Abstract 299: Effect of Start Position and Compression Depth on Mechanical CPR Hemodynamics in Swine

Introduction: Mechanical devices offer the ability to provide consistent fixed-depth chest compressions during CPR. Although compression depth is considered a primary determinant of CPR quality, the influence of other device settings has received less attention. Accordingly, we evaluated the combined effect of compression depth and device start position on CPR hemodynamics in a porcine model of cardiac arrest (CA). Methods: Swine (n=119) were subjected to 7-10 min of CA following electrical induction of ventricular fibrillation. CPR was subsequently performed manually (target peak aortic pressure: 100 mmHg; n=73) or with a mechanical compression system (LUCAS 3.1, Stryker; n=46). Within the mechanical CPR group, animals received 102 compressions/min using either factory default settings (“QuickFit” automated suction cup start position; compression depth: 2.1”; n=13) or custom settings (manual suction cup start position; compression depth: 1.8”; n=33). Aortic pressure (Ao), coronary perfusion pressure (CPP), and regional cerebral oxygen saturation (rSO 2 ; via near infrared spectroscopy) were compared between groups after 1 min of CPR. Results: Mechanical CPR with automated suction cup start position and compression depth of 2.1” resulted in significantly higher peak Ao and CPP than mechanical CPR with manual start position and compression depth of 1.8” ( Table ). Compared with manual CPR, only mechanical CPR with automated start position and compression depth of 2.1” led to a higher CPP. However, cerebral rSO 2 values fell from 61±1 % at baseline to 49±1 % during CA (p<0.01) and did not increase during CPR in any group. Conclusion: Compared with a manual start position and compression depth of 1.8”, use of the LUCAS “QuickFit” feature and compression depth of 2.1” led to a significantly higher CPP during mechanical CPR. Future studies are necessary to determine if differences persist during prolonged CPR with and without concomitant vasopressor administration.

The prototype of A Forklift Robot Based on AGV System and Android Wireless Controlled for Stacked Shelves

The paper aims to build a prototype of an automatic forklift robot that can collect and place goods in the stacking shelves, that are monitored remotely using an Android-based device. The method used is AGV (Automated Guided Vehicle) on this forklift robot prototype to adjust its positions, by following a line that preset trajectory for stacking shelf positions, where this forklift robot can collect and place goods. The robot navigation system uses a photodiode for the line follower system, and for storage of goods, it uses the proximity sensors detecting the presence of goods on miniature stacking goods and decide where it can store a good or not on that designated cell of the stacking shelf. The miniature of stacking shelves is two by three cells. The control of the robot has two input controllers. One is on a robot itself. The other was on handheld based on Android operating systems, which control remotely using the wireless system with Bluetooth protocol. The results of the discussion on paper, the forklift robot could manage the task given as the predefined line to a followed parameter of stacking shelves with two by three-stack configuration for collect and place goods into their positions, the average time for the robot to collecting and placing goods on stacking from standing still position to stacking shelf then back to the robot origin position. It resulted in the shortest processing time around 43 seconds and the longest time around 45,3 seconds from the start position to stacking shelf position.

Start position of a sloping hydraulic jump

ABSTRACT Although sloping hydraulic jumps are frequent in energy dissipators, there are few studies regarding this type of phenomenon. Since the jump is accompanied by violent impacts and sudden variations of velocity and pressure, it is important to know the region where the phenomenon will occur, in order to make a safe and economic design possible. In this paper, a methodology for the determination of the start position of the sloping jump along a Creager spillway is introduced. It was verified that this position is a function of both the incident Froude number and the submergence factor.

Accurate internal representation of eye position in saccade planning

Fixation position changes slightly after each blink (Lau &amp; Maus, 2019). We investigated whether these changes affect subsequent saccades. We tested if the oculomotor system uses an internal representation of eye position to plan a saccade. Naïve participants (N = 12) made 10° visually-guided (VG) and memory-guided (MG) saccades to a dot target presented to the left or right of fixation. Participants blinked once (blink) or remained fixated (no-blink) before an auditory cue instructed them to saccade to the target. We hypothesized that if participants had access to an eye position signal at the onset of their saccade, blink-induced position shifts should be corrected for. The alternative hypothesis was that without such an internal eye position signal, blink-induced position shifts should correlate with landing positions. This was not the case either in VG or MG saccades. Saccades started more forward from fixation for MG than VG saccades and landed more backward of the target for MG than VG saccades. Blinking did not contribute to these positional differences. Instead, blinks enlarged both saccade amplitudes. MG amplitudes were also smaller than VG amplitudes. We found no correlation between starting and landing errors across saccades. Hence, start position changes did not influence saccade landing errors. Our results suggest that to plan accurate saccades, the oculomotor system uses an internal representation of eye position that is updated after each blink. Although blinking was introduced to increase eye position changes, it did not influence saccade starting nor landing positions.

HAS-QA: Hierarchical Answer Spans Model for Open-Domain Question Answering

This paper is concerned with open-domain question answering (i.e., OpenQA). Recently, some works have viewed this problem as a reading comprehension (RC) task, and directly applied successful RC models to it. However, the performances of such models are not so good as that in the RC task. In our opinion, the perspective of RC ignores three characteristics in OpenQA task: 1) many paragraphs without the answer span are included in the data collection; 2) multiple answer spans may exist within one given paragraph; 3) the end position of an answer span is dependent with the start position. In this paper, we first propose a new probabilistic formulation of OpenQA, based on a three-level hierarchical structure, i.e., the question level, the paragraph level and the answer span level. Then a Hierarchical Answer Spans Model (HASQA) is designed to capture each probability. HAS-QA has the ability to tackle the above three problems, and experiments on public OpenQA datasets show that it significantly outperforms traditional RC baselines and recent OpenQA baselines.

Strategi Menemukan Jalan Keluar Labirin dengan Waktu Tercepat Menggunakan Metode DFS

Depth-first search algorithm are blind search process and deepen search follow a single track until found goal. Maze is complicated network way and tortuous, also have many deadlock. Maze often become a challenge in a game like puzzle, which one there’s an object in start position have find way out on specify position. in this journal we’ll discuss about utilization DFS on maze and fastest time to find way out.