Interactive Physically-Based Simulation of Roadheader Robot

Roadheader is an engineering robot widely used in underground engineering and mining industry. Interactive dynamics simulation of roadheader is a fundamental problem in unmanned excavation and virtual reality training. However, current research is only based on traditional animation techniques or commercial game engines. There are few studies that apply real-time physical simulation of computer graphics to the field of roadheader robot. This paper aims to present an interactive physically-based simulation system of roadheader robot. To this end, an improved multibody simulation method based on generalized coordinates is proposed. First, our simulation method describes robot dynamics based on generalized coordinates. Compared to state-of-the-art methods, our method is more stable and accurate. Numerical simulation results showed that our method has significantly less error than the game engine in the same number of iterations. Second, we adopt the symplectic Euler integrator instead of the conventional fourth-order Runge-Kutta (RK4) method for dynamics iteration. Compared with other integrators, our method is more stable in energy drift during long-term simulation. The test results showed that our system achieved real-time interaction performance of 60 frames per second (fps). Furthermore, we propose a model format for geometric and robotics modeling of roadheaders to implement the system. Our interactive simulation system of roadheader meets the requirements of interactivity, accuracy and stability

Simultaneous evolutionary expansion and constraint of genomic heterogeneity in multifocal lung cancer.

Recent genomic analyses have revealed substantial tumor heterogeneity across various cancers. However, it remains unclear whether and how genomic heterogeneity is constrained during tumor evolution. Here, we sequence a unique cohort of multiple synchronous lung cancers (MSLCs) to determine the relative diversity and uniformity of genetic drivers upon identical germline and environmental background. We find that each multicentric primary tumor harbors distinct oncogenic alterations, including novel mutations that are experimentally demonstrated to be functional and therapeutically targetable. However, functional studies show a strikingly constrained tumorigenic pathway underlying heterogeneous genetic variants. These results suggest that although the mutation-specific routes that cells take during oncogenesis are stochastic, genetic trajectories may be constrained by selection for functional convergence on key signaling pathways. Our findings highlight the robust evolutionary pressures that simultaneously shape the expansion and constraint of genomic diversity, a principle that holds important implications for understanding tumor evolution and optimizing therapeutic strategies.Across cancer types tumor heterogeneity has been observed, but how this relates to tumor evolution is unclear. Here, the authors sequence multiple synchronous lung cancers, highlighting the evolutionary pressures that simultaneously shape the expansion and constraint of genomic heterogeneity

Physicochemical properties of stabilized sewage sludge admixtures by modified steel slag

Cement stabilization is used extensively to solidify sludge. However, previous studies suggest that the organic acids in sludge can restrain the hydration processes of cementitious materials. This study presents a new binder (steel slag based materials) whose effectiveness of stabilization was investigated on sewage sludge. Several series of tests for solidified sludge were conducted including the moisture content, compressive strength, shear force, permeability, and toxicity characteristic leaching (TCLP). The result shows that the stabilization effect of physicochemical properties of stabilized sewage by S1* (content 90% steel slag) were better than that of cement. With 20% S1, the moisture content of the sludge could be reduced to 30% at 20+1°C for 7 days; The compressive strength was 74.5 kappa and the permeability coefficient was 5.03 × 10–5 (cm/s); The TCLP was below the limit value. The hydration products of paste and solidified sludge at 1, 3, 14, 28, and 90 days were analyzed by XRD, SEM, and energy spectroscopy to distinguish ettringite/iron ettringite in S1 solidified sludge. the result shows the Needle-like ettringite of S1 possess high iron content and may be Fe–Aft

A Combined Method for Predicting the Boron Deposited Mass and the CIPS Risk

CIPS is a shift in the axial power towards the bottom half of the core, also known as axial offset anomaly (AOA), which results from the deposited of corrosion products during an operation. The main reason of CIPS is the solute particles especially boron compounds concentrated inside the porous deposit. The impact of CIPS is that the axial power distribution control may be more difficult and the shutdown margin can be decreased simultaneously. Besides, it also requires estimated critical condition (ECC) calculations to account for the effects of AOA. In this article, thermal-hydraulic subchannel code and boron deposit model have been combined to analyze the CIPS risk. The neutronics codes deal with the generation of homogenized neutron cross section as well as the calculation of local power factor. A simple rod assembly is analyzed with this combined method and simulation results are presented. Simulation results provide the boron hideout amount inside crud deposits and power shapes. The obtained results clearly show the power shape suppression in regions where crud deposits exist, which is a clear indication of CIPS phenomenon. And the CIPS effects on CHF have also been investigated. Result shows a margin of DNBR decrease in the crud case

Theoretical formulation and performance analysis of a novel hydride heat Pump(HHP) integrated heat recovery system

Many efforts are dedicated globally to industrial waste heat recovery in hope of reducing energy consumption and pollutants emission. A novel system composed of direct heat exchanger and hydride heat pump is proposed to achieve this target, which could effectively utilize the sensible heat from a process stream at both high and low temperatures. In this paper, we present the fundamental procedure for formulation of such a system, including heat duty assignment, working pair screening and cycle modification. In addition, thermodynamic analysis on the performance of the integrated system is conducted, and the results exhibit the possibility of building competitive alternative to existing absorption heat exchanger (AHE). Finally, the impacts of design variables and material properties on system performance are discussed, providing a benchmark for applying such a system on various occasions

Whether and how congested is a road? Indices, updating strategy and a vision‐based detection framework

Abstract Traffic congestion detection method based on surveillance video is gradually widely used in intelligent transportation systems (ITS). Due to complex challenges such as weather change, vehicle occlusion, camera jitter, camera installation location, and so on, current methods are difficult to balance in real time and accuracy. Here, a new real‐time and robust traffic congestion detection framework and a vision‐based multi‐dimensional congestion detection model are proposed. Firstly, the framework introduces an object detector based on the lightweight convolutional neural network (CNN) and an efficient multi‐object IoU‐like tracker to obtain traffic dynamic information in real time. Then, traffic density, traffic velocity, and duration of instantaneous congestion are defined and a multi‐dimensional congestion detection model is established. Furthermore, an adaptive updating strategy of dynamic parameters is investigated. Finally, in multiple groups of comparative experiments, the framework is verified to be applicable to a variety of lightweight CNN detectors and IoU‐like trackers. The precision and recall of the multi‐dimensional congestion model can reach 95.1% and 92.1% respectively, with 43FPS. The comparative experimental results show that the proposed method is real‐time, more robust and accurate, and can be employed for online traffic congestion detection based on surveillance video