NI LabVIEW Research Articles

Design and Development of a Robust Control Platform for a 3-Finger Robotic Gripper Using EMG-Derived Hand Muscle Signals in NI LabVIEW

Robots are increasingly present in everyday life, replacing human involvement in various domains. In situations involving danger or life-threatening conditions, it is safer to deploy robots instead of humans. However, there are still numerous applications where human intervention remains indispensable. The strategy to control a robot can be developed based on intelligent adaptive programmed algorithms or by harnessing the physiological signals of the robot operator, such as body movements, brain EEG, and muscle EMG which is a more intuitive approach. This study focuses on creating a control platform for a 3-finger gripper, utilizing Electromyography (EMG) signals derived from the operator’s forearm muscles. The developed platform consisted of a Robotiq three-finger gripper, a Delsys Trigno wireless EMG, as well as an NI CompactRIO data acquisition platform. The control process was developed using NI LabVIEW software, which extracts, processes, and analyzes the EMG signals, which are subsequently transformed into control signals to operate the robotic gripper in real-time. The system operates by transmitting the EMG signals from the operator's forearm muscles to the robotic gripper once they surpass a user-defined threshold. To evaluate the system's performance, a comprehensive set of regressive tests was conducted on the forearm muscles of three different operators based on four distinct case scenarios. Despite of the gripper’s structural design weakness to perform pinching, however, the results demonstrated an impressive average success rate of 95% for tasks involving the opening and closing of the gripper to perform grasping. This success rate was consistent across scenarios that included alterations to the scissor configuration of the gripper.

Whole body vibration and rider comfort determination of an electric two-wheeler test rig

Background Two-wheeled vehicles are the major mode of transportation in India. Such vehicles are exposed to excessive vibration on the road when compared to four-wheeled vehicles. However, the research on the reduction of whole body vibration in the case of two-wheelers is not explored in detail. The present study predicts rider comfort in the case of an electric two-wheeler as per ISO 2631-1, by obtaining the finding the weighted acceleration at the strategic locations of vibration at the test rig. Methods An electric two-wheeler test rig is used in the study. The values of acceleration from the test rig in running conditions are obtained by using NI LabVIEW 2019. The drive cycle of the electric vehicle (EV) test rig is controlled by Sync sols’ EV lab software. Obtaining the weighted root mean square (RMS) acceleration from running the test setup, it is compared with the ISO 2631-1 standard to obtain the rider comfort. Results Loading area, traction motor, base mount, and suspension were found to be the strategic points of vibration. Frequency weighted RMS acceleration of 0.3 to 0.4 m/s2 obtained at these points are prone to cause discomfort for the rider. Vehicle speed, road profile, and duration of exposure were found to be important parameters affecting the rider’s comfort. A maximum of 4.6 m/s2 amplitude was observed. The loading area, which corresponds to a rider’s seat in actual vehicle, is important and reduction of these vibrations make the ride comfortable for the rider. Suspension and base mount of the test rig are found to be uncomfortable observing the weighted RMS acceleration. Conclusions A suitable damping technique design is very much essential in reducing these vibrations and improve the rider comfort, as many more non-deterministic vibrations are prone to cause dis-comfort in case of actual on road riding conditions.

Development of an H2 fuel cell electrochemical system powered by Escherichia coli cells

Because of the growing high importance of the development of biocatalytic fuel cell (FC) technologies for renewable energy-producing and testing systems for medical or environmental purposes, in this study, we constructed and demonstrated an H2 FC voltammeter working with graphite sample testing micro-strips and based on Escherichia coli microbial cells. Presented H2 FC voltammeter that provides fast and precise testing of bio-electrochemical possible reactions in biosamples for H2 and other gases, is automated with software which works in NI LabVIEW programming environment, has amplifier cascade system with high internal resistance, temperature controlling and resistance cascade. Microbial Hydrogenase (Hyd) enzymes reversibly catalyze the formation and oxidation of H2. Isolation and characterization of O2-tolerant [NiFe]-hydrogenases (Hyds) have given rise to new concepts in H2 FC. Escherichia coli and [NiFe]-Hyds can be applied as a biocatalyst anode in biofuel cells (BFCs). We evaluated the efficiency of applying the 3 µl (1.5 mg cell dry weight) E. coli intact cells or crude extracts on 0.5 cm2 as anode catalyzers in the bio-electrochemical system. The highest electrical potential (up to 0.7 V) was achieved with bacterial whole cells, which were grown on glucose and glycerol.

ENERGY TECHNOLOGY OF DAIRY PRODUCTS QUALITY ASSESSMENT USING IMPEDANCEMETRY

The article examines the peculiarities of milk quality research using the impedance method. Impedance is a complex parameter that characterises the interaction of the electric current with milk. The authors have developed a methodology based on the specified method to assess the quality of dairy products and have created a hardware and software complex that makes it possible to analyse the quality of dairy products. The research, conducted using the developed hardware and software complex, revealed several regularities characterising different types of milk. These regularities demonstrate the relationship between the impedance signal and the milk fat index. Analysis of the obtained data allowed us to identify differences in impedance between samples with varying fat content and origin from different manufacturers. The developed experimental setup prototype enabled the following research stages: checking the change in voltage during the passage of an alternating electric current through milk. This work used the AFS Sensor DAQ data acquisition system, designed for sensor control projects and which runs with NI LabVIEW software, for data output. The authors tested the installation while investigating the impedance of dairy products with different fat content and from multiple manufacturers. During the experiment, we measured the impedance and capacitance of the samples, and the obtained data became available on a PC for further analysis. The aim was to study the electrical properties of dairy products and their dependence on the composition and manufacturer. The obtained results represent valuable information for dairy product production and quality control. It is possible to use them to optimise production processes, ensure stable product quality, and improve consumer characteristics of dairy products. The obtained data contribute to a deeper understanding of the relationship between the impedance signal and the composition of dairy products, which can lead to the development of new methods of analysis and evaluation of the quality of food products. In addition, these studies have implications for food science and nutrition. Keywords: dairy products, milk quality, impedancemetry, electrical measurements, hardware and software complex.

SIMULATION OF MULTIPOINT CONTACT UNDER THERMOELECTRIC TESTING

The article presents the results of modeling a multipoint contact in the thermoelectric method of testing. Sources of thermoelectromotive force (thermoEMF) have shown different influences, according to their type, on the load characteristics of the equivalent source obtained by parallel connection of several thermocouples as shown in the explanatory figures. The presented model is implemented in the NI LabVIEW package, which is freely available. The model was verified on three types of thermocouples (copper-constantan, copper-nichrome, and chromel-alumel), which have been connected in parallel in different quantities. The calculated load characteristics of the equivalent sources differ from the experimental ones by no more than 6%. The results of modeling the load characteristics of the equivalent thermoEMF sources obtained by parallel connection of different quantities of two types of thermocouples are presented. It is shown that in order to obtain reliable data, it is necessary to provide an equivalent source load of at least 1 kOhm.

Optical Inspection of Mounted Printed Circuit Board using National Instruments Software

The topic of the given task based on the optical opposition of a mounted printed circuit board using National Instruments software. During the inspection, 7 types of resistors, 3 types of integrated circuits, barcodes and text were detected. The results of the detection have been visualized and a Microsoft Excel scan report has been exported. The optical inspection was carried out using the National Instruments Vision Development Module and LabVIEW development environments.

Whole body vibration and rider comfort determination of an electric two-wheeler test rig.

Two-wheeled vehicles are the major mode of transportation in India. Such vehicles are exposed to excessive vibration on the road when compared to four-wheeled vehicles. However, the research on the reduction of whole body vibration in the case of two-wheelers is not explored in detail. The present study predicts rider comfort in the case of an electric two-wheeler as per ISO 2631-1, by obtaining the finding the weighted acceleration at the strategic locations of vibration at the test rig. An electric two-wheeler test rig is used in the study. The values of acceleration from the test rig in running conditions are obtained by using NI LabVIEW 2019. The drive cycle of the electric vehicle (EV) test rig is controlled by Sync sols' EV lab software. Obtaining the weighted root mean square (RMS) acceleration from running the test setup, it is compared with the ISO 2631-1 standard to obtain the rider comfort. Loading area, traction motor, base mount, and suspension were found to be the strategic points of vibration. Frequency weighted RMS acceleration of 0.3 to 0.4 m/s 2 obtained at these points are prone to cause discomfort for the rider. Vehicle speed, road profile, and duration of exposure were found to be important parameters affecting the rider's comfort. A maximum of 4.6 m/s 2 amplitude was observed. The loading area, which corresponds to a rider's seat in actual vehicle, is important and reduction of these vibrations make the ride comfortable for the rider. Suspension and base mount of the test rig are found to be uncomfortable observing the weighted RMS acceleration. A suitable damping technique design is very much essential in reducing these vibrations and improve the rider comfort, as many more non-deterministic vibrations are prone to cause dis-comfort in case of actual on road riding conditions.

Design of a Cavity Pressure Monitoring System for Plastic Injection Molding

This work aims to create an instrument that allows the measurement of cavity pressure during plastic injection molding. The designed device is intended to contribute to the equipment inventory of the Polymer Technology Laboratory at Sapientia EMTE, Faculty Târgu Mureș. The design criteria were the ease of mounting and use. The system was implemented with two load cells, two HX711 amplifiers, an ESP32-based microcontroller and a corresponding computer user interface. The user interface was developed using National Instruments LabVIEW program and finalized as a stand-alone application. During the design steps, attention was also paid to the practical applicability of the system.

Combined Experimental and Numerical Approach for the Thermal Heat Exchange Investigation of Li-Ion Cells for Automotive Applications

Lithium-ion (Li-ion) battery is an advanced technology in the field of electrochemical energy storage, but its management constitutes one of the most intriguing challenges for electric vehicles. Many parameters need to be controlled and managed and many aspects need to be optimised. This work presents a methodology for laboratory characterization of Nickel Manganese Cobalt (NMC) Lithium-Ion batteries suited for automotive applications. The purpose consists of obtaining a detailed description of the electrical and thermal behaviour of a single battery cell to provide an accurate model (static, dynamic, and thermal) that could ensure optimized real-time battery management by a management system for several battery packs. A battery testing system was built using a bidirectional power supply and a software/hardware interface was implemented within the National Instruments LabVIEW environment that monitors current, voltage and temperature sensors. This dedicated laboratory equipment can be used to apply and report charging/discharging cycles according to the user-defined load profile. A bidimensional CFD dynamic condition/transient simulation in the Ansys FLUENT environment was performed to study the heat thermal fluxes generated by a determined current value in the battery cells, and the results have been compared to the experimental data for validation.

Laboratory Tester for Relay Contacts Lifespan

This study focuses on the implementation of a laboratory relay contact life tester using a data acquisition board and the NI LabVIEW development environment. Tested reed contacts have a lifespan of several million cycles. Therefore the biggest challenge was creating a tester that would be able to verify the ability of the contact to achieve a defined number of cycles at the required current load in a maximum of a few days. This study describes all the interesting discoveries that came up during the implementation of the tester. It also highlights the influence of coil current and switching frequency on contact settling time and lifespan.

Design of a memristor-based neuron for spiking neural networks

The primary objective of neuromorphic system design is to surpass limitations in energy efficiency and scaling of classical von Neumann computing systems, through the emulation of animals’ nervous systems. This is achieved by conducting calculations in memory and encoding information in impulse signals, ultimately leading to enhanced adaptability. Adhering to these principles allows for improved energy efficiency and computational speed when solving machine learning problems, encompassing biomedical applications, embedded systems, and cyber-physical systems. Functional blocks modeling the main elements of the central nervous system, namely neurons and synapses, offer an advantage in implementing learning on a chip. The use of memristive electronic components, capable of altering their resistance based on the charge flowing through them, opens new doors for hardware implementation of neuromorphic systems. These devices offer advantages over conventional transistor electronics with respect to power consumption, component density, and performance. To achieve optimal results, the architecture of neuromorphic systems should be optimized at the device level. Memristive components are utilized to create neurons and synapses. This thesis is specifically focused on producing memristive neuron-like spike signal generators. Previously, memristive neurons were crafted using a locally active element comprised of vanadium dioxide VO2, which incorporated a negative differential resistance section of the IV-curve. One of the recent advancements in this field is a spiking neuron with frequency adaptation [1]. Its drawbacks, however, involve separating the memristive and locally active elements physically, resulting in higher energy consumption and decreased integration quality. In [2], models of memristive neurons with minimal complexity are introduced, which incorporate the Leaky Integrate-and-Fire principle. However, the circuits presented require the application of negative voltage pulses to a DC battery to reset the memristor to its initial high-resistance state. This limitation restricts its sphere of application in neuromorphic systems. This paper proposes a model of a neuron that overcomes these limitations by using the negative differential resistance of the memristor to generate spikes, along with integrating supplementary circuit components to sustain the resistive switching cycles of the memristor. The neuron model under consideration is implemented using the NI Multisim 14.2 SPICE environment and has been verified in the NI LabVIEW 2022 tool environment. The equations of the modified model of the generalized mean metastable switch of the memristor with self-directed channel [3] represent the current in the memristor branch of the neuron equivalent circuit. The simplicity of the equivalent circuitry of the neuron is attained by merging all the nonlinear features necessary for spike generation into one memristor model. The experimental phase of the study employed obtainable memristors from Knowm Corporation and the laboratory prototyping platform NI ELVIS III. The investigation of the proposed neuron model was accomplished through the application of sinusoidal and rectangular input signals. The refractory time of the neuron model was calculated. The chosen stack of computer simulation and semi-natural modeling technologies is applied within the research-driven design concept of electronic devices. This approach considers the importance of refining the properties and identification of the design object or its components during the development cycle.

Rotational Speed Measurement of a Shaft Using Infrared Sensor with NI Data Acquisition system and LabVIEW

Rotational speed measurement is the process of determining the number of rotations completed in a unit time. Generally, it is measured in Hertz, radians per second and rotations per minute (RPM). Rotational speed measurement is very critical parameter in condition monitoring, speed control, and supervision of rotational equipment like generators and turbines. This paper presents an alternate method of measuring the speed of a shaft using one of the cheapest infrared sensors available in Nepalese market. The principle of measurement of speed is on the basis of reflected and absorbed infrared light which is acquired using data acquisition unit of National Instrument. The signal processing has been carried out in a LabVIEW program and speed of shaft has been verified using the other optical sensors.

Development of an Automated Hall Effect Experimentation Method for the Electrical Characterization of Thin Films

There has been drastic growth in the microelectronics industry in the recent past. The performance of these materials is influenced by their structural, electrical, and optical properties among others, depending on their applications. Therefore, the need to conduct measurements of the semiconductor characteristics precisely, quickly, and conveniently cannot be overstated. Some of the desirable features of measurements include usability, accuracy, resolution, repeatability, and consistency which cannot be assured with manually operated systems. This study strived to design and interface an automated computer-aided four-point probe test equipment that characterizes materials to determine their electrical properties. A four-point probe head, an electromagnet, NI Keithley model 6220 Precision current source, model 7001 switch, model 2182A Nanovoltmeter, and model 7065 Hall Effect card instruments were interfaced with the NI LabVIEW program running in a computer through a GPIB hub to a PC USB for its full control. The four-probe head was utilized to probe the samples with a square symmetry that was adopted for the measurement of the semiconductor properties. Reliability tests were conducted on a standard P-type Germanium sample. The collected data was within 0.32% of the expected results. This work forms a basis for automating similar systems that were inherently designed to be operated manually. Keywords: Automated Hall Effect, manually operated systems, Hall angle, thin films, string manipulation routines.

Automatic batch weighing and discharge system using NI LabVIEW and auger mechanism

In the fields of metallurgy, mining, coking, rubber, ceramics, cement, grain, friction materials, and other industries, the batching process is crucial. It's sometimes referred to as the "throat" of industrial firms' manufacturing processes. It eloquently contrasts its significance throughout the entire production process. The first objective of the paper is to explain the workings of a dynamic control system for the process of automatic batch weighing and ingredient discharge. The control system is designed to provide maximum flexibility. It incorporates dual sensory mechanisms to more accurately monitor the density and amount of ingredients in a particular container and aid in the precise mixing of different ingredients as per the formula. Innumerable formulas can be added to the system. The second object of the paper is to compare the effects of incorporating NI LabVIEW in designing the control system. We have reviewed NI LabVIEW software with SCADA software on variables such as load handling capacity, computational ability, processing speed, flexibility of programming, and ease of use for the system and the users. The PLCs and process control systems (PCSs) are used to automate the production process. There are integrated system solutions available today for the automation hardware of PLCs and process control systems. It has been demonstrated that the system is inexpensive, highly reliable, and simple to use. It significantly reduces labour intensity and eliminates health risks from dust in the production line for friction materials. It is worthwhile to encourage use across relevant industries. The Auger mechanism is used for the precise discharge of ingredients.

LabVIEW based ECG simulator and automatic detection system for cardiac disorders

In the present age, most cardiac arrhythmias are emerging due to irregular rhythmic conditions of the heart. Diagnosis of cardiac arrhythmias plays an essential role in the survival of the human race. If rhythms of nature are distorted for any reason, it leads to several variations or abnormalities known as heart arrhythmias. Irregular heartbeats lead to anomalous P, QRS, and T values, which the patient’s ECG can follow. The growing well-being concerns, especially for cardiac arrhythmias, reflect the requirement of creating a cheap and convenient ECG detection system. The most common heart conditions are tachycardia, bradycardia, atrial fibrillation, myocardial infarction and many other cardiac disorders. These diseases are one of the most significant causes of death worldwide. There is much research for recognizable proof of cardiovascular diseases utilizing ECG diagnostic toolbox and different software. So, in this project, the idea is to design an Automatic Disease Detection System on LabVIEW to detect various cardiac abnormalities such as Atrial Flutter (AF), Supraventricular Tachycardia (SVT), Left Bundle Branch Block (LBBB), Ventricular Fibrillation (VF), Myocardial Infarction (MI), Hyperkalaemia and Digoxin by comparing it to the normal ECG signal. So for this, NI LABVIEW (2018) software has been used for designing. This Automated Disease Detection System, hopefully, gives the best accurate and fast results which are low cost, effective, efficient, easy handled and high accuracy rate detection system which can be used in hospitals for medical professionals.

Methods of control and measurements of components of the onboard radio engineering complex

Background. The relevance of the topic of this work is due to the need to increase the reliability and quality of the results of measuring control of modules of various levels and antenna arrays that are part of the onboard radio engineering complex, as well as to increase the reliability and parametric efficiency of the radio engineering complex. Aim. Development of a method and methodology for integrated control of radio frequency modules of the 1st, 2nd, and 3rd levels in the process of design, production and testing based on modern automation tools and processes. Methods. Full-scale experiment, computer modeling, programming, expert assessments, research, autonomous and acceptance tests were used. Results. The choice of a working control model was made. Based on it, an automated workplace has been developed. It includes integrated control and measuring equipment controlled by special software, a software package with a common operator interface. To control the testing process, a software package has been developed that automatically sets the necessary operating modes of the modules and provides a stimulating signal from the vector network analyzer in accordance with the specified parameters. After the end of testing, a test report is generated and printed. If the modules are tested for compliance with technical specifications, the protocol is formed in accordance with GOST. The test sequence is developed using the NI TestStand automated testing environment, and the routines that control the operating modes of the products are developed using C/C++ and NI LabVIEW graphical development tools. The automated workplace implements the following functions: functional electronic control of circuits and nodes of radio frequency modules and the product as a whole, electrical integrity control of circuits and nodes of frequency modules, programming of digital components, conducting complex tests of frequency modules, conducting complex tests of antennas and antenna arrays. The developed algorithm includes a stage of self-testing of the automated workplace hardware. After entering the necessary information, a step-by-step cycle of monitoring the module parameters is started. It begins with the connection of the device under test to the automated workplace and ends with the preparation of a test report and a message about the validity or unfitness of the totality of the measured parameter values. The final conclusion about the operability of the control object is made automatically after the measurement of all parameters is completed in the form of a pop-up dialog box. It contains one of two mutually exclusive statements: «Control successfully passed», «Control failed». Conclusion. The algorithm and methodology of automated control and tuning have been developed, which allows to increase the reliability and accuracy (by 5–15 %) of the measurement results of the electrical parameters of the PPM at the stages of tuning and testing. A software package for automated control has been developed. An automated control workplace has been developed.

Whole body vibration and rider comfort determination of an electric two-wheeler test rig

Background: Two-wheeled vehicles are the major mode of transportation in India. Such vehicles are exposed to excessive vibration on the road when compared to four-wheeled vehicles. However, the research on the reduction of whole body vibration in the case of two-wheelers is not explored in detail. The present study predicts rider comfort in the case of an electric two-wheeler as per ISO 2631-1. Methods: An electric two-wheeler test rig is used in the study. The values of acceleration from the test rig in running conditions are obtained by using NI LabVIEW 2016. The drive cycle of the electric vehicle (EV) test rig is controlled by Sync sols’ EV lab software. Obtaining the root mean square (RMS) acceleration from running the test setup, it is compared with the ISO 2631 standard to obtain the rider comfort. Results: Loading area, traction motor, base mount, and suspension were found to be the strategic points of vibration. RMS acceleration of 0.2 g to 3.29 g obtained at these points are prone to cause discomfort for the rider. Vehicle speed, road profile, and duration of exposure were found to be important parameters affecting the rider’s comfort. A maximum of 3.28 g amplitude was observed at the loading area at no load condition. The loading area, which corresponds to a rider’s seat in actual vehicle, is important and reduction of these vibrations make the ride comfortable for the rider. Suspension and base mount of the test rig are found to be uncomfortable observing the RMS acceleration. Conclusions: A suitable damping technique design is very much essential in reducing these vibrations and improve the rider comfort, as many more non-deterministic vibrations are prone to cause dis-comfort in case of actual on road riding conditions.

Health Monitoring of Flat Slab Using NI Labview

Abstract: Structural health monitoring techniques are widely used for detection of risky zone or faults or defects on the body whether it may be Building, bridges, steel structure like truss and towers, and also in the machines and in equipments like plane, trains etc. Wired techniques are mostly useful for the bodies which are small and in which the structure is physically in touch with the sensors whereas in wireless technique, the sensors are not in physically in touch with the structure. Sensors are then to be fixed at appropriate location of the designed flat slab. For monitoring the considered flat slab program is done using NI LabVIEW. The sensors are connected to the computer via My DAQ. The slab is then monitored for the working loads and the data is obtained in the form of graphs.

Portable Electrochemical Impedance Spectroscopy Device Implementation for Alzheimer's Disease-Related Protein

Electrochemical impedance spectroscopy (EIS) is an electrochemical technique to measure the impedance varieties of a system based on the alternating current (AC) potential frequency. This technique is high accuracy and frequently used to distinguish the influences between different components. The charge transfer resistance and electric double layer phenomenon commonly occur in these components in an electrochemical system. A slight sinusoidal excitation with multiple frequency has been used to process the phenomenon to impedance values. These values can be simulated as an equivalent circuit to analyze the resistance, amplitude, and phase angle in the actual electrochemical cell [1].Alzheimer's disease (AD) is the most common form of amnesia. However, AD symptoms are difficult to be conscious of in the early stage, and current screening methods are hard to popularize. Current research generally agrees that AD has a considerable association with beta-amyloid (Aβ) precipitation [2]. Aβ is the proteolytic fragment derived from amyloid precursor proteins (APP). These proteins can be used to screen the pathogenesis of AD. Biological detection chips capture these proteins and then use commercial instruments for detection. The biological detection chips are fabricated using a screen-print-electrode (SPE) chip which contains three gold electrodes, and the fabrication steps show in Figure 1(A). 11-Mercaptoundecaoic acid (11-MUA) was used as a self-assembled monolayer (SAM) to functionalize the biological chip. 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC)/N-hydroxysuccinimide (NHS) have been used to activate the functional group on SAM to bond the antibody for specific detection of Aβ. Finally, block the residual activated groups with ethanolamine. After modifying the sensors, the protein was applied for measuring immediately.This research aims to popularize a portable device that can achieve rapid and accurate monitoring of early AD. In this study, an AD5933 chip was utilized as the main chip for a portable EIS device to compare with the commercial instrument CHI920D. This integrated circuit chip can be applied as an impedance meter. The AD5933 is embedded on a board that contains an analog front-end (AFE) circuit. This AFE circuit can bias the direct current (DC) output from 1.48 V to 0 V and AC output from 1.98V p-p to 0.1V p-p. Also, we applied a 25 kHz clock signal for AD5933 to sweep frequency in 10 Hz to 20 Hz with 1 Hz resolution. This portable device is controlled by NI Myrio1900, and NI LabVIEW system with a laptop, as shown in Figure 1(B).To analyze the signal gathered from the Aβ, a simulated actual electrochemical cell with an equivalent current is needed. The test frequency has been fixed between 10 to 20 Hz due to the limitation of AD5933. The original Randles circuit is the frequently used circuit applied to impedance calculation [1]. To optimize the current there are some conditions that can be ignored. For instance, the resistance of redox solution (RΩ), which the resistance is too small compared with the whole electrochemical cell. The Warburg element (Zw) gives a low impact on the frequency interval. Thus, the circuit can be optimized and simplified as a simple parallel resistor-capacitor (RC) circuit. To evaluate system performance, the same biological detection chips were used for both portable devices (Figure 1(B)) and CHI920D (Figure 1(C)). Both calculation method is sample charge transfer resistance (Rct) divided by blocking charge transfer resistance (Rct). The correlation coefficient R2 of these sensors is 0.97 (Figure 1(D)), which means the portable system result is identical to the CHI920D.In conclusion, our research accomplished the system with low frequency and low AC and DC measuring, indicating a higher sensitivity for early AD detection. The limitation of this research is the biological detection chips. These modified chips are time-sensitivities that lead to conservation becoming difficult. The experimental results suggest that this portable is a potential candidate for wide screening of AD, and arranging the portable device in pairs might accomplish the point of care of AD. Furthermore, this device can also develop with different biomarkers, depending on additional antibody modification. Bard, A.J., et al., Fundamentals and applications. Electrochemical Methods, 2001. 2(482): p. 580-632.Hardy, J.A., et al., Alzheimer's disease: the amyloid cascade hypothesis. Science, 1992. 256(5054): p. 184-186. Figure 1

Study of the dependence of the natural frequencies of a rotor system with a vertically positioned rotor on the preload

The article discusses the possibility of using a method for determining the preload force for trust and radial bearings of spindle assemblies for high-speed milling. Previously, a method was developed and tested for determining the preload force of bearing supports on high-speed grinding electrospindles with a horizontal spindle.
 The object of study is a support with angular contact bearings 7004 ACD_P4A SKF and a vertical rotor. An information-measuring system has been developed, which consists of PCB 352C34 vibration acceleration sensors, a Vishay 614 force sensor, an NI-cRIO-9056 controller, NI 9250, NI 9237 and NI 9481 modules, and software written in the National Instruments Labview language.
 The system of test actions has been improved due to its automation. Test effects began to be carried out using a solenoid with a core, which was controlled by an NI controller and developed software. Due to this, the same time delay was formed between the test action and the start of recording the vibration acceleration signal.
 Vibration acceleration signals are obtained for the entire preload range. To study the controllability of the unit, two vibration acceleration sensors were used: with a parallel and perpendicular arrangement of the axes of the direction of vibration and test action. For the first and second groups of vibration accelerations, spectral transformations were carried out, and the amplitude-frequency characteristics of the assembly were obtained for the entire range of preload values.
 As a result of the work, it was concluded that the presented methodology and criteria are applicable to high-speed milling spindle assemblies with a vertical rotor. It is also shown that this technique can be automated.