Qwen Technical Report

Large language models (LLMs) have revolutionized the field of artificial intelligence, enabling natural language processing tasks that were previously thought to be exclusive to humans. In this work, we introduce Qwen, the first installment of our large language model series. Qwen is a comprehensive language model series that encompasses distinct models with varying parameter counts. It includes Qwen, the base pretrained language models, and Qwen-Chat, the chat models finetuned with human alignment techniques. The base language models consistently demonstrate superior performance across a multitude of downstream tasks, and the chat models, particularly those trained using Reinforcement Learning from Human Feedback (RLHF), are highly competitive. The chat models possess advanced tool-use and planning capabilities for creating agent applications, showcasing impressive performance even when compared to bigger models on complex tasks like utilizing a code interpreter. Furthermore, we have developed coding-specialized models, Code-Qwen and Code-Qwen-Chat, as well as mathematics-focused models, Math-Qwen-Chat, which are built upon base language models. These models demonstrate significantly improved performance in comparison with open-source models, and slightly fall behind the proprietary models.Comment: 59 pages, 5 figure

A Review of Cavitation Erosion on Pumps and Valves in Nuclear Power Plants

The cavitation erosion failure of pumps or valves induces the low efficiency and reduced service life of nuclear reactors. This paper reviews works regarding the cavitation erosion of pumps and valves in the nuclear power industry and academic research field. The cavitation erosion mechanisms of materials of pumps and valves are related to the microstructure and mechanical properties of the surface layer. The cavitation erosion resistance of austenitic stainless steel can be ten times higher than that of ferritic steel. The cavitation erosion of materials is related to the hardness, toughness, and martensitic transformation capacity. Erosion wear and erosion–corrosion research is also reviewed. Erosion wear is mainly influenced by the hardness of the material surface. Erosion–corrosion behavior is closely connected with the element composition. Measures for improving the cavitation erosion of pumps and valves are summarized in this paper. The cavitation erosion resistance of metallic materials can be enhanced by adding elements and coatings. Adhesion, inclusion content, and residual stress impact the cavitation erosion of materials with coatings

Design and Experiment Evaluation of Load Distribution on the Dual Motors in Cam-Based Variable Stiffness Actuator with Helping Mode

This paper presents a novel cam-based variable stiffness actuator (VSA). It significantly differs from its counterparts in that the external load distributes on its two motors with a small difference. It is a feasible method to improve VSA’s output power, especially in compact joints, such as rehabilitation devices. The stiffness adjustment involves a spring-balanced crank-slider mechanism with a variable-length base frame. Its tunable node is the common node for force decomposition, synthesis, stiffness adjustment, and position control by setting it at the common groove of two differential variable-pitch cams. The paper establishes analytical expressions among the pressure angle of the cam pitch curve, load distribution, and its crucial design indexes and constraints. Based on this, the pitch curve synthesis method is put forward to optimize the load distribution. In addition, a reasonable tradeoff can be easily made by locally adjusting the cam pressure angle. So, the dual motors can work against the output load together in the same direction with a close amount. In the fabricated prototype, current stratification caused by the unstable friction direction has been observed. The estimation results of motor frictionless current matched the designed load distribution behavior

Design of a Robotic Fish Propelled by Oscillating Flexible Pectoral Foils

Abstract-This paper proposed a new method of designing a flexible biomimetic fish propelled by oscillating flexible pectoral fins. The molding soft body is adopted in the robotic fish. Pneumatic artificial muscles are utilized as driving sources and two ribs with distributed flexibility as main parts of the propulsive mechanism. The leading edge locomotion profile of the flexible pectoral fin in air is studied experimentally, and the flapping locomotion in water is observed too. Finally, the effectiveness of the proposed method is illustrated by the experiment. It shows that the robotic fish can realize self-driven, and it can swim at a speed of 0.18m/s~0.20m/s after optimization. I. INTRODUCTION ONSIDERABLE work has been focused on fishes, for their high velocity, high efficiency and excellent maneuverability are expected properties for man-made under-water vehicles. Many biomimetic prototypes now are propelled by fluctuation body and caudal fins, as considered having higher velocity and efficiency. The pectoral fins are usually used to assist propulsion, improve mobility and control balance. Many fishes get turning moments by their oscillating pectoral fins which can also help to keep their motion being with high maneuvering capability and excellent stability [1], [2]. Recently, study on elasmobranches shows that fishes with flexible pectoral fins can swim with reduced thrust requirements and increased efficiency as a result of hydrodynamic ground effect and their low energy consumption gliding in water It is experimentally proved that flexibility can reduce resistance, lower noise and increase efficiency of fish A flexible bionic fish propelled by oscillating flexible foils, potentially occupies the futures of high efficiency, excellent stability and maneuverable capability. That is the reason the robotic fish in this paper was developed. II. NATURE PROTOTYPE The biological template for the design is cownosed ray, a typical elasmobranch using large flat flexible pectoral fins as the source for propulsion, as shown in As one of the most efficiency swimmers in the ocean, cownosed rays can migrate over long distance at a speed of 0.6~0.8 times of its body length per second with high efficiency Cownosed rays swim in a mode called "Mobuliform", characterized by the low flapping frequency, less than half a wave presented on fins at any specific time and the foils never extending below the ventral body axis during the down-stroke It is considered to be an ideal creature to imitate in developing a robotic fish utilizes oscillating flexible pectoral foils as the propulsive source, featuring stability and maneuverability. III. WHOLE-FLEXIBLE BODY DESIGN The whole-flexible body is designed according to the Design of a Robotic Fish Propelled by Oscillating Flexible Pectoral Foils Yueri Cai, Shusheng Bi, Lige Zhang, Jun Ga

Design and Experiment Evaluation of Load Distribution on the Dual Motors in Cam-Based Variable Stiffness Actuator with Helping Mode

This paper presents a novel cam-based variable stiffness actuator (VSA). It significantly differs from its counterparts in that the external load distributes on its two motors with a small difference. It is a feasible method to improve VSA’s output power, especially in compact joints, such as rehabilitation devices. The stiffness adjustment involves a spring-balanced crank-slider mechanism with a variable-length base frame. Its tunable node is the common node for force decomposition, synthesis, stiffness adjustment, and position control by setting it at the common groove of two differential variable-pitch cams. The paper establishes analytical expressions among the pressure angle of the cam pitch curve, load distribution, and its crucial design indexes and constraints. Based on this, the pitch curve synthesis method is put forward to optimize the load distribution. In addition, a reasonable tradeoff can be easily made by locally adjusting the cam pressure angle. So, the dual motors can work against the output load together in the same direction with a close amount. In the fabricated prototype, current stratification caused by the unstable friction direction has been observed. The estimation results of motor frictionless current matched the designed load distribution behavior

Pressure Relief-Type Overpressure Distribution Prediction Model Based on Seepage and Stress Coupling

At present, great progress has been made in the prediction of undercompaction and fluid expansion overpressure. However, in recent years, the field has frequently encountered pressure relief-type overpressure. Different from primary overpressure, such as undercompaction and fluid expansion, this type of overpressure belongs to secondary overpressure, which has a certain concealment in response to seismic velocity and logging data. Based on this, a geological analysis model of pressure relief-type overpressure was established according to the seepage and stress coupling theory. The model can realize the prediction of pressure relief range and pressure distribution, which provides a new way to predict this kind of overpressure. The influence of the laws of porosity, permeability, and geological movement on pressure relief were analyzed. The research results provide a new method for the prediction of pressure relief-type overpressure and improving the basic guarantee of safe and efficient drilling

Pressure Relief-Type Overpressure Distribution Prediction Model Based on Seepage and Stress Coupling

At present, great progress has been made in the prediction of undercompaction and fluid expansion overpressure. However, in recent years, the field has frequently encountered pressure relief-type overpressure. Different from primary overpressure, such as undercompaction and fluid expansion, this type of overpressure belongs to secondary overpressure, which has a certain concealment in response to seismic velocity and logging data. Based on this, a geological analysis model of pressure relief-type overpressure was established according to the seepage and stress coupling theory. The model can realize the prediction of pressure relief range and pressure distribution, which provides a new way to predict this kind of overpressure. The influence of the laws of porosity, permeability, and geological movement on pressure relief were analyzed. The research results provide a new method for the prediction of pressure relief-type overpressure and improving the basic guarantee of safe and efficient drilling