A New Calculation Method of Cutterhead Torque Considering Shield Rolling Angle

The existing cutterhead torque calculation method usually simplifies the characteristics of the shield, which ignores the rolling angle. In this paper, the cross-river shield project of Wuhan Metro Line 8 is taken as the research focus. Firstly, the measured data of the cutterhead torque (CT), the rolling angle and rotation direction were analyzed. Then on this basis, the penetrability, tunneling thrust, and rolling angle were taken as the influential factors to analyze CT sensitivity. Finally, based on the theoretical calculation model, a modified solution of CT was obtained considering the rolling angle. The results show that the rolling angle can be reduced to zero by changing the direction of the cutterhead rotation; the rolling angle has a greater impact on CT than the other two factors as shown through the analysis of the range difference and Statistical Product and Service Solutions (SPSS) method. As the absolute value of the rolling angle increases, CT also increases, and the relationship between them is linear. To a certain extent, the rolling angle of the shield can reflect the difficulty of tunneling and the running status. By monitoring the rolling angle of the shield, the prediction of CT can be more in line with the actual construction conditions.

Active positioning system based on hall-effect sensors

The paper investigates the behavior of Hall-effect sensors (HES) operating in microwave frequency range. In order to evaluate the capabilities of small radars based on HES’s, the calculation of HES output voltage dependence on microwave intensity is carried out. It is shown that at power flow density I(t) = 10 μW/cm2 (a permissible value for a long-term human body exposure) the single GaAs sensor output Hall voltage U H ~ 0.03 μV. It is also demonstrated that integration of signals with due regard for their delays (as in the case of range-difference radar systems) gives an opportunity to obtain electromagnetic image of any point within the antenna coverage area with centimeter-level accuracy. The paper describes the experimental assembly and estimates the distances to the detected contrasting objects.

Survival and pleurodesis outcome in patients with malignant pleural effusion – a systematic review

Malignant pleural effusion (MPE) is a common condition that presents with progressive breathlessness. Long term solutions are often required due to recurrence of effusion after simple drainage. Pleurodesis is one of the main options resorted to for long term control of MPE. There is data to suggest there may be a survival benefit for patients with MPE who achieve successful pleurodesis. A systematic review was carried out to explore this correlation and results suggest that there could be a survival difference according to pleurodesis outcome in patients with MPE. Fifteen studies (reported in 13 papers) were included; 13 (86.6%) of the studies showed survival difference in favour of pleurodesis success. The median [interquartile range] difference in survival between the two groups among the different studies was five [3.5–5.8] months. Most of the included studies suffered moderate to severe risk of bias and, thus, large prospective studies of patients undergoing pleurodesis are required to ascertain this effect.

Survival and pleurodesis outcome in patients with malignant pleural effusion – a systematic review

Malignant pleural effusion (MPE) is a common condition that presents with progressive breathlessness. Long term solutions are often required due to recurrence of effusion after simple drainage. Pleurodesis is one of the main options resorted to for long term control of MPE. There is data to suggest there may be a survival benefit for patients with MPE who achieve successful pleurodesis. A systematic review was carried out to explore this correlation and results suggest that there could be a survival difference according to pleurodesis outcome in patients with MPE. Fifteen studies (reported in 13 papers) were included; 13 (86.6%) of the studies showed survival difference in favour of pleurodesis success. The median [interquartile range] difference in survival between the two groups among the different studies was five [3.5–5.8] months. Most of the included studies suffered moderate to severe risk of bias and, thus, large prospective studies of patients undergoing pleurodesis are required to ascertain this effect.

On the Choice of Base Geometry, Type and Design of the Passive Radio Reflector of the Passive Radar Complex

The article presents the methods that allow to solve the problem of choosing the type, design and installation location of a control terrain feature (CTF) – a passive radio reflector for a passive location complex that implements the angle measuring-range-difference method. The CTF module must reflect the signal at angles from 0° to 180° (upper hemisphere). The rationale for choosing the CTF module and base geometry will allow receiving signals from jammers from any direction relative to the main receiving point

Calculation of spatial target coordinates in range-difference passive radars by the Levenberg – Marquardt method

This article studies and analyzes the results of applying numerical iterative methods for solving nonlinear equation systems (Newton, modified Newton's method, gradient descent, sequential iterations, Levenberg – Marquardt), compiled and used to calculate the rectangular spatial coordinates of radio emission sources in range-difference passive radars of various configurations (incorporating from 3 to 4 receiving points). The aim of the research was to determine the optimal number of receiving points and to select the most effective algorithm for coordinate transformations of the vector of observed parameters (a set of range difference estimates from radio emission sources to the corresponding pairs of receiving points) into the vector of measured parameters (rectangular spatial coordinates). The following parameters were used as comparison criteria: passive radar working area (a part of space where the deviation of target coordinate estimates from their true values does not exceed the maximum tolerable values); average error in calculating spatial coordinates in the working area; iterations number of coordinate calculation in the analyzed part of space. Upon completing a comparative analysis of obtained characteristics and dependencies, we concluded that it is optimal to include four receiving points in a range-difference passive radar and use the Levenberg – Marquardt method to calculate the spatial coordinates of radio emission sources.

Investigating the Consistency of Uncalibrated Multispectral Lidar Vegetation Indices at Different Altitudes

Multi-spectral (ms) airborne light detection and ranging (lidar) data are increasingly used for mapping purposes. Geometric data are enriched by intensity digital numbers (DNs) and, by utilizing this additional information either directly, or in the form of active spectral vegetation indices (SVIs), enhancements in land cover classification and change monitoring are possible. In the case of SVIs, the indices should be calculated from reflectance values derived from intensity DNs after rigorous calibration. In practice, such calibration is often not possible, and SVIs calculated from intensity DNs are used. However, the consistency of such active ms lidar products is poorly understood. In this study, the authors reported on an ms lidar mission at three different altitudes above ground to investigate SVI consistency. The stability of two families of indices—spectral ratios and normalized differences—was compared. The need for atmospheric correction in case of considerable range difference was established. It was demonstrated that by selecting single returns (provided sufficient point density), it was possible to derive stable SVI products. Finally, a criterion was proposed for comparing different lidar acquisitions over vegetated areas.