Centrifugal compressor anti-surge control system modelling

<span>From the middle of XX century, natural gas is an important mineral, widely used in the energy sector. Transportation of natural gas is carried out via gas pipeline networks and compression stations. One of the key features which need to be implemented for any centrifugal gas compressor is a surge protection. This article describes the method and develops software application intended for simulation and study of surge protection system of a centrifugal compressor used in modern gas compression stations. Within the article research method, modelling environment’s block diagram, proposed algorithms and results are described. For surge cases control and prediction, Anti-surge control block implemented which based on practical experience and centrifugal compressor theory. To avoid complicated energy balancing differential equations the volumetric flow calculation algorithm proposed which is used in combination with Redlich-Kwong equation of state. Developed software’s adequacy test performed through modeling of one-stage gas compression scheme at rated speed with comparison of parameters with reference commercial software and verification of the anti-surge control system.</span>

Composite Control Strategy of Output Current of LCL Photovoltaic Grid-Connected Inverter

In order to further optimize the output current harmonic suppression effect of photovoltaic grid-connected inverters, a composite control strategy of LCL type photovoltaic grid-connected inverter output current is proposed. This strategy combines proportional complex integral (PCI) control and repetitive control (RC) in parallel, draws a composite control block diagram, introduces a transfer function, and designs PCI and RC control parameters. Prove that the compound control can reduce current harmonics, achieved the purpose of reducing the steady-state error of the fundamental frequency. And adopts a new PCI composite control strategy, which helps to save the cost of the control system. By building the MATLAB/Simulink simulation platform and establishing the PCI+RC composite control model of LCL photovoltaic grid-connected inverter, the comparison of the simulation results shows that compared with the PI+RC control strategy, the total harmonic distortion rate of the grid-connected current is reduced by 25.77. %, significantly improving the quality of grid-connected current.

The Effect of Temperature and Heating Time of Roselle Extract (Hibiscus Sabdariffa L) Powder Solution on Growth Inhibition of Staphylococcus aureus ATCC 25923

The main ingredients of roselle (Hibiscus sabdariffa L.) which have antioxidant and antibacterial effect were anthocyanins, and flavonoids. Flavonoid compounds were unstable at high temperatures. Meanwhile, the processing of roselle extract powder into ready-to drink or food preparations generally requires the thermal processes. The aims of this study were to determine the effect of temperature and heating time of roselle extract powder solution on the inhibition of microbial growth of Staphylococcus aureus ATCC 25923. The method of this study uses a ready-to- process roselle powder extract sample. The roselle extract powder solution in a screw cap tube was heated at a temperature of 40°C, 50°C, 60°C, 70°C, 80°C, and 90°C on a waterbath, with heating times at each temperature were 15 minutes and 30 minutes. Anti bacterial activity of the sample solution was measured based on the ability to inhibit the growth of Staphylococcus aureus ATCC 25923 by the agar-well diffusion method. The inhibition zone of the sample was measured by caliper. The result of this study showed that inhibition zones caused by the sample that had been heated at those temperature for 15 minutes were 9.55±0.70 mm, 9.53 ±0.04 mm, 9.70±0.14 mm, 9.68±0.24 mm, 10.10±0.14 mm, and 10.25±0.21 mm. Meanwhile, after heating for 30 minutes the inhibition zones were 10.08±0.25 mm, 10.20±0.28 mm, 10.43±0.18 mm, 10.08±0.18 mm, 10.78±0.04 mm, 9.70±0.14 mm. Two ways statistical test ANOVA Randomized Control Block Design with 95% confidence level was used to prove that there was a significant difference berween the mean inhibition zones of each sample. The conclution of this research was, the temperature in the range of 40 -90 oC has no effect on the anti-bacterial activity of the sample. However, the heating time of the sample affected the antibacterial activity of the roselle extract powder solution against Staphylococcus aureus ATCC 25923.

Dynamic Stability and Flight Control of Biomimetic Flapping-Wing Micro Air Vehicle

This paper proposes an approach to analyze the dynamic stability and develop trajectory-tracking controllers for flapping-wing micro air vehicle (FWMAV). A multibody dynamics simulation framework coupled with a modified quasi-steady aerodynamic model was implemented for stability analysis, which was appended with flight control block for accomplishing various flight objectives. A gradient-based trim search algorithm was employed to obtain the trim conditions by solving the fully coupled nonlinear equations of motion at various flight speeds. Eigenmode analysis showed instability that grew with the flight speed in longitudinal dynamics. Using the trim conditions, we linearized dynamic equations of FWMAV to obtain the optimal gain matrices for various flight speeds using the linear-quadratic regulator (LQR) technique. The gain matrices from each of the linearized equations were used for gain scheduling with respect to forward flight speed. The reference tracking augmented LQR control was implemented to achieve transition flight tracking that involves hovering, acceleration, and deceleration phases. The control parameters were updated once in a wingbeat cycle and were changed smoothly to avoid any discontinuities during simulations. Moreover, trajectories tracking control was achieved successfully using a dual loop control approach. Control simulations showed that the proposed controllers worked effectively for this fairly nonlinear multibody system.

A typological investigation of personality: Trait expression as a coordinated system of self-regulatory functioning

<p>Many researchers contend that the intra-individual configuration of multiple traits, as compared to isolated trait dimensions, more effectively capture personality functioning at the level of the individual. Moreover, it is argued that by identifying subsets of individuals with similar trait-profiles, we can shed light on the generative mechanisms that underlie the expression and functioning of personality. Notably, self-regulatory systems of ego-resiliency and ego-control, as developed by Block and Block, comprise a valuable theoretical foundation for the development and interpretation of personality types. However, much of the literature on this topic is theoretically ambiguous, and is afflicted with inconsistent empirical outcomes across studies. The focus of the present thesis is to advance the empirical assessment and theoretical interpretability of personality profiles. More particularly, comparisons between three and four profile solutions are at the core of the current investigations. These competing models reflect differing interpretations of ego-domains; the three profile model embodies a proposed curvilinear relationship between the two constructs, whereas the four profile model emphasises the roles of ego-resiliency and ego-control as distinct mechanisms with unique outcomes. In Study 1, Latent Profile and Latent Transition Analyses were conducted using the Six-Factor Model of personality. Three and four profile solutions were developed and compared using measures of model fit, profile interpretability, longitudinal stability, and predictive ability. In Study 2, the replicability of both solutions when using the Five-Factor Model was examined, along with the comparative value of the Six- as opposed to Five-Factor Model in profile identification. Finally, in Study 3, the interpretability of the four profile solution as reflecting differentiated domains of ego-functioning was assessed using established measures of ego-resiliency and ego-control. Across all three studies, profiles were considered using a novel approach utilising both continuous and categorical methodologies. Rather than treating profiles as entirely discrete groupings of personality functioning, the present investigation considers convergence with prototypical profiles in terms of degree. The current findings provide support for the four profile solution as a more coherent and theoretically validated model as compared to the three profile solution. Specifically, although both solutions demonstrated good fit and longitudinal stability, the four profile solution was associated with more theoretically interpretable outcomes. These findings were consistent when using both the Six- as well as Five-Factor Model of personality; however, omission of the sixth trait resulted in a reduction in profile precision and explanatory power. Finally, in Study 3, selected exemplars of the four profile solution converged onto theoretically consistent domains of high/low ego-resiliency and ego-control. Block and Block’s model of ego-resiliency and ego-control provides a clear unifying framework for the intra-individual structuring of a four profile configuration of traits. Ego-constructs are flexible self-regulatory mechanisms that develop through reciprocal person-environmental transactions. The current results are therefore suggestive of a hierarchical relationship between ego-domains and personality traits, whereby traits form the basic parameters of a dynamic self-regulatory system. Moreover, the combination of continuous and categorical methodologies presently used strengthens the conclusions and arguments in this thesis.</p>

A typological investigation of personality: Trait expression as a coordinated system of self-regulatory functioning

<p>Many researchers contend that the intra-individual configuration of multiple traits, as compared to isolated trait dimensions, more effectively capture personality functioning at the level of the individual. Moreover, it is argued that by identifying subsets of individuals with similar trait-profiles, we can shed light on the generative mechanisms that underlie the expression and functioning of personality. Notably, self-regulatory systems of ego-resiliency and ego-control, as developed by Block and Block, comprise a valuable theoretical foundation for the development and interpretation of personality types. However, much of the literature on this topic is theoretically ambiguous, and is afflicted with inconsistent empirical outcomes across studies. The focus of the present thesis is to advance the empirical assessment and theoretical interpretability of personality profiles. More particularly, comparisons between three and four profile solutions are at the core of the current investigations. These competing models reflect differing interpretations of ego-domains; the three profile model embodies a proposed curvilinear relationship between the two constructs, whereas the four profile model emphasises the roles of ego-resiliency and ego-control as distinct mechanisms with unique outcomes. In Study 1, Latent Profile and Latent Transition Analyses were conducted using the Six-Factor Model of personality. Three and four profile solutions were developed and compared using measures of model fit, profile interpretability, longitudinal stability, and predictive ability. In Study 2, the replicability of both solutions when using the Five-Factor Model was examined, along with the comparative value of the Six- as opposed to Five-Factor Model in profile identification. Finally, in Study 3, the interpretability of the four profile solution as reflecting differentiated domains of ego-functioning was assessed using established measures of ego-resiliency and ego-control. Across all three studies, profiles were considered using a novel approach utilising both continuous and categorical methodologies. Rather than treating profiles as entirely discrete groupings of personality functioning, the present investigation considers convergence with prototypical profiles in terms of degree. The current findings provide support for the four profile solution as a more coherent and theoretically validated model as compared to the three profile solution. Specifically, although both solutions demonstrated good fit and longitudinal stability, the four profile solution was associated with more theoretically interpretable outcomes. These findings were consistent when using both the Six- as well as Five-Factor Model of personality; however, omission of the sixth trait resulted in a reduction in profile precision and explanatory power. Finally, in Study 3, selected exemplars of the four profile solution converged onto theoretically consistent domains of high/low ego-resiliency and ego-control. Block and Block’s model of ego-resiliency and ego-control provides a clear unifying framework for the intra-individual structuring of a four profile configuration of traits. Ego-constructs are flexible self-regulatory mechanisms that develop through reciprocal person-environmental transactions. The current results are therefore suggestive of a hierarchical relationship between ego-domains and personality traits, whereby traits form the basic parameters of a dynamic self-regulatory system. Moreover, the combination of continuous and categorical methodologies presently used strengthens the conclusions and arguments in this thesis.</p>

Collection and processing of bearing vibration data for their technical condition classification by machine learning methods

An experimental research facility has been developed to receive vibration signals from mechanisms with installed rolling bearings. A control block for all equipment has been created. For the repeatability of the experiment, an external microcontroller with a programmed proportional-integral-derivative regulator was used. Experiments were carried out to obtain initial data for different types of bearings. The processed data were grouped and made publicly available for further research. It is proposed to solve the problem of emergency stop of the generator, arising during operation due to bearings worn, by recognizing the pre-emergency conditions of rotary rig based on the use of advanced machine learning techniques: to highlight the signs of vibration and build clusters according to the degree of worn.

Enhanced MAC controller architecture for 2D processing based on FPGA with configurable resource allocation

The bulks of image processing algorithms are either two-dimensional (2D) or confined by their very nature. As a result, the 2D convolution function has a large impact on picture processing requirements. The methodology of 2D convolution and media access control (MAC) design can also be used to perform a variety of image processing tasks, and even as picture blurring, softening, and feature extraction. The main goal of this research is to develop a more efficient MAC control block-based 2D convolution architecture. This 2D algorithm can be implemented in hardware using fewer modules, multipliers, adders, and control blocks, resulting in significant hardware savings and look up table (LUT) reductions. The simulations were run in Verilog, and the Xilinx Vertex family field programmable gate array (FPGA) was used to build and test them. The recommended 2D convolution architectural solution is significantly faster and consumes significantly less hardware resources than the traditional 2D convolution implementation. The proposed architecture will result in technology that saves a substantial amount of processing time when it comes to LUTs.

Novel Service Efficiency Evaluation and Management Model

Numerous scholars have invested in the research of service innovation management, hoping to find a more objective and scientific service efficiency evaluation and management model so as to stride forward towards the goal of smart innovation management. In the service operating system, the multi-workstation service operation is one of the common service operation models. Some studies have pointed out: apart from a good service attitude, the service operation time of each workstation is a key factor which measures the performance of the workstation’s service operation. Therefore, this paper proposed a standardized concept with a service operation efficiency evaluation index. This index is not only convenient and easy-to-use, but it also has a one-to-one mathematical relationship with the performance achievement rate. Next, the radar evaluation chart was employed to evaluate the service efficiency of each workstation. First, according to the upper confidence limit and the required value of the index, the minimum value (MV) of the index estimator was derived and marked on each radar line; at the same time, all MVs were connected to form a control block. When the point estimate of the index does not fall into the control block of the radar chart, it represents that the service operation efficiency of the workstation has not reached the required level, so it needs to be improved. Because this model can directly compare the point estimate of the index with the MV, it can judge whether the service operation efficiency reaches the required level. In this way, the advantage of simple and easy-to-use point estimate can be maintained, and the risk of misjudgment caused by sampling errors can be reduced as well, which is helpful for the service industry to move towards the goal of intelligent innovation management. This method is not only applied to the performance evaluation of the multi-workstation service operation process but also applicable to the performance evaluations of other service operations.

Model Predictive Control for Automatic Carrier Landing with Time Delay

This paper focuses on the problem of automatic carrier landing control with time delay, and an antidelay model predictive control (AD-MPC) scheme for carrier landing based on the symplectic pseudospectral (SP) method and a prediction error method with particle swarm optimization (PE-PSO) is designed. Firstly, the mathematical model for carrier landing control with time delay is given, and based on the Padé approximation (PA) principle, the model with time delay is transformed into an equivalent nondelay one. Furthermore, a guidance trajectory based on the predicted trajectory shape and position deviation is designed in the MPC framework to eliminate the influence of carrier deck motion and real-time error. At the same time, a rolling optimal control block is designed based on the SP algorithm, in which the steady-state carrier air wake compensation is introduced to suppress the interference of the air wake. On this basis, the PE-PSO delay estimation algorithm is proposed to estimate the unknown delay parameter in the equivalent control model. The simulation results show that the delay estimation error of the PE-PSO algorithm is smaller than 2 ms, and the AD-MPC algorithm proposed in this paper can limit the landing height error within ±0.14 m under the condition of multiple disturbances and system input delay. The control accuracy of AD-MPC is much higher than that of the traditional pole assignment algorithm, and its computational efficiency meets the requirement of real-time online tracking.