Dynamic Modeling and Vibration Characteristics for a High-Speed Aero-Engine Rotor with Blade Off

Blade off that occurs during operation will generate a sudden imbalance excitation and make the rotor become inertially asymmetric, which leads to large instantaneous impact load and induces more complex rotor dynamic phenomena. In order to study the transient dynamic characteristics for complex rotors suffering from blade off, a mathematical model for solving the response of the gas generator rotor in the aero-turboshaft engine is established based on the FE method and DOF condensation, in which the complex structural characteristics, transient impact load, and inertia asymmetry of the rotor are considered. The complex impeller structure is modeled by piecewise linear fitting with cylindrical beam elements and tapered beam elements. Without loss of generality, the modeling method suitable for complex rotors is verified through a general complex test rotor with modal experiments. Based on this, the responses are solved for carrying out parametric studies and an understanding of the transient dynamic characteristics of the rotor under the extreme working conditions of blade off. The results show that the blade off has a great impact effect on the time-domain waveform, frequency components, and rotor orbits. At the instantaneous stage after blade off, the complex motion is composed of synchronous motion and some lower-order natural modes excited by blade off. Although the transient responses with blade off at different rotational speeds have similar time-varying characteristics, the impact factor is sensitive to the rotating speed. Most important is that the parameter of the blade off location will not only have a significant effect on the impact factor, but also on the frequency spectrum. These dynamic characteristics as well as impact effect provide certain guidance for the fault recognition and dynamic analysis to these complex rotors suffering blade off.

Percentiles and a cyclic approach for the methodology of scenario predictive planning of promising specialization of the region

Subject. This article deals with the problems of development of promising sectors of the region's economy. Objectives. The article aims to assess the scenarios of regional industry changes considering a case study of the automotive industry. Methods. For the study, we used the bootstrap and wavelet transform techniques. Results. The article describes the inertial, pessimistic (5% percentile) and optimistic (95% percentile) scenarios for the development of the automotive industry and shows the range of possible deviations of industry dynamics in the case of the influence of external and internal factors. Conclusions. The proposed methodology and tools make it possible to fine-tune the forecast of industry dynamics, take into account its possible deviations from a predetermined path during the year, and put management decisions into proactive impact effect.

Development of Multipurpose Biowaste Shredder Machine

The scope of this project was to design and develop a Shredder machine with focus on chopping of coconut leaves, areca leaves, this chopped powder to prepare the vermin compost. The project began with collection of information and data on user lifestyle and current process by which they perform their job. Concepts were developed with reference of four different shredder machine and operating processes. Concept was developed considering the safety factor users operating environment and maintenance. Considering the users’ needs and buying capacity, a prototype was fabricated. The machine consists of singlephase motor, bearings, structural frame, cutter and shaft. The machine frame is built using mild steel and CPM REX M4 HC is used for cutter tip preparation. Four cutters are mounted on shafts, which rotates.. The power from the electrical motor is transmitted to cutter shaft through a belt drive. Cut is made inside the chopping house due to the effect of tensile, friction, and impact effect in chopping process. The coconut leaves get chopped and powder is collected. The possible outcomes of this project are:  The working efficiency is set to increase with the reduced power to weight ratio.  Reduced cost with reliable performance output.  People with different physics can be accommodated on this equipment. Keywords: Agro waste; shredding machine; Cutter, Single-Φ motor, shaft.

Dynamic responses of reinforced concrete slabs under sudden impact loading

Reinforced concrete (RC) slabs may be subjected to low-velocity impact effect in their service lives. In this study, it is aimed to investigate dynamic responses of two-way rc slabs. So, a total of 6 slabs with 500x500, 550x550 and 600x600 mm side lengths and having same thickness are both experimentally and numerically investigated under low velocity impact loading. Two different reinforcement configurations are used in the production of each slab. A drop test setup is designed for the experimental study. Besides, measurement devices such as accelerometer, lvdt, dynamic load cell, data logger and optic photocells are used in the experimental program. Experiments on the specimens are carried out for the same level of impact energy. Acceleration, displacement and impact load values of slabs are presented by time dependent graphs. In addition, cracks and deformations are observed during tests. In the numerical part of this study, a detailed finite element procedure where explicit dynamic analysis is performed by Abaqus finite elements software is established. The simulations are performed for each test specimen under impact effect and analysis results are used in the verification of experimental results. The relationship between experimental and numerical studies is comparatively examined in terms of crack patterns and average ratios of accelerations, displacements, impact loads. Finally, it is considered that the proposed numerical model could be used in the evaluation of experimental results under impact loading.

Will Innovation of Pharmaceutical Manufacturing Improve Perceived Health?

By taking 22 OECD countries from 2010 to 2017 as sample, we study the effect of pharmaceutical manufacturing innovation on perceived health by using the panel Tobit model from the entire sample and sub-samples, respectively, as well as analyze their transmission channels by adding moderating effect. Based on the above, we get the following results: first, the pharmaceutical manufacturing innovation 4 years ago has a positive influence on perceived health, which means the improvement of perceived health is closely related to pharmaceutical manufacturing innovation 4 years ago. Second, pharmaceutical manufacturing innovation has a heterogeneous impact on perceived health, which, including the size and direction of the impact effect, is mainly reflected in different pharmaceutical manufacturing innovation levels, population aging degrees, and education levels. Third, income level can positively regulate the impact of pharmaceutical manufacturing innovation on perceived health.