Shaping the Design Features of a Dynamometer for Measuring Resistance Biaxial Components of Symmetrical Coulters

The article lays out the methodology for shaping the design features of a strain gauge transducer, which would make it possible to study forces and torques generated during the operation of symmetrical seeder coulters. The transducers that have been known up until now cannot be used to determine forces and torques for the coulter configuration adopted by the authors. For this purpose, the design of the transducer in the form of strain gauge beams was used to ensure the accumulated stress concentration. A detailed design was presented in the form of a 3D model, along with a transducer body manufactured on its basis, including the method for arranging the strain gauges thereon. Moreover, the article discusses the methodology of processing voltage signals obtained from component loads. Particular attention was paid to the methodology of determining the load capacity of the transducer structure, based on finite element method (FEM). This made it possible to choose a transducer geometry providing the expected measurement sensitivity and, at the same time, maintaining the best linearity of indications, insignificant coupling error, and a broad measurement range. The article also presents the characteristics of the transducer calibration process and a description of a special test stand designed for this purpose. The transducer developed within the scope of this work provides very high precision of load spectrum reads, thus enabling the performance of a detailed fatigue analysis of the tested designs. Additionally, the versatility it offers makes it easy to adapt to many existing test stands, which is a significant advantage because it eliminates the need to build new test stands.

MODELING OF STATIC CHARACTERISTICS OF PNEUMATIC STRAIN GAUGE TRANSDUCER

Measuring instruments that implement the pneumatic principle of measurement, have a number of significant advantages: small dimensions of the measuring equipment, allowing to produce multiparameter control in a limited size of the working area, insensitivity to vibration, simplicity of design and reliability. The disadvantage of pneumatic converters is a discrete output electrical signal, which does not allow the processing of measurement results. In this regard, it seems appropriate to investigate the pneumatic-electric Converter, which includes a jet pneumatic and differential strain gauges, which allows to obtain an analog electrical signal at the output. The article describes the design and principle of operation pneumoenteritis Converter to control the diameter of the part. Pneumotensometric Converter converts the change in the diameter of the part in the movement of the nozzle, which causes a change in the force of the air jet on the beam, its deformation and, accordingly, a change in the resistance of he strain gauge. An expression describing the stoic characteristic of the transducer and allowing to determine the force of the air jet impact on the load cell from the gap between the nozzle and the beam, the air pressure and the nozzle diameter is given. The results of modeling the static characteristics of the Converter at different combinations of design parameters are given, the values of straight sections of characteristics and sensitivity are determined, their comparative evaluation is given.

OPTIMIZATION OF SEMICONDUCTOR PRESSURE TRANSDUCER WITH SENSITIVE ELEMENT BASED ON “SILICON ON SAPPHIRE” STRUCTURE

The paper is devoted to the study of the process of optimizing the semiconductor strain-gauge transducer on the structure of the SOS. As an object of the study, an elastic membrane-type element with a semiconductor strain-gauge in the form of a silicon-on-sapphire structure was used. To study the surface of sapphire, the optical photolithography method was used. In the framework of this task, the control parameters and the quality parameters of the serially-manufactured strain gauge were determined. The paper describes the methodology for multicriteria optimization, and also an optimization calculation for the strain-gauge on the SOS. The main result is the obtaining of Pareto-optimal design variants that exceed the basic variant by all quality criteria.

Analysis and Probabilistic Modeling of the Stationary Ice Loads Stochastic Process With Lognormal Distribution

Until recent times researchers who investigated ice loads stochastic processes usually stated the fact of normal distribution for them. In the paper the model of a stationary stochastic process with a lognormal distribution for ice loads is offered. This model relates to the strain gauge transducer ice loads measurements as well as to some examples considered in different papers that were published earlier. For this model dependencies of the autocorrelation function were found that allows to simulate the ice loads process relatively easily. The procedure of such a simulation is described in details and the example of the analysis and simulation ice loads measurements is provided.

Strain gauge measurement of rein tension during riding: a pilot study

A pilot study was performed using a strain gauge transducer intercalated between the bit and the left rein to measure rein tension dynamically during riding. The strain patterns consisted of a series of spikes with frequencies corresponding to two per stride in walk and trot and one per stride in canter. The highest tension recorded in each gait was 43 N at walk, 51 N at trot and 104 N in canter. Based on the results of this study, it is recommended that the methodology should be adapted so that both reins are instrumented simultaneously, data are transmitted telemetrically to eliminate the need for a tether connecting the horse to the computer, and kinematic data are synchronized with the rein tension recordings.

Dual effects of acupuncture on gastric motility in conscious rats

The effects of manual acupuncture on gastric motility were investigated in 35 conscious rats implanted with a strain gauge transducer. Twenty (57.1%) rats showed no cyclic groupings of strong contractions ( type A), whereas 15 (42.9%) rats showed the phase III-like contractions of the migrating motor complex ( type B) in the fasting gastric motility. Acupuncture at the stomach (ST)-36 (Zusanli), but not on the back [Weishu, bladder (BL)-21], increased the peak amplitude of contractions to 172.4 ± 25.6% of basal in the type A rats ( n = 20, P < 0.05). On the other hand, the motility index for 60 min after the acupuncture was not affected by the acupuncture in this group. On the contrary, acupuncture decreased the peak amplitude and motility index to 72.9 ± 14.0% and 73.6 ± 16.2% in the type B rats ( n = 15, P < 0.05), respectively. The stimulatory and inhibitory effects of acupuncture observed in each type were reproducible on the separate days. In 70% of type A rats, acupuncture induced strong phase III-like contractions lasting for over 3 h that were abolished by atropine, hexamethonium, atropine methyl bromide, and vagotomy. Naloxone significantly shortened the duration of the stimulatory effects from 3.52 ± 0.21 to 1.02 ± 0.15 h ( n = 3, P < 0.05). These results suggest that acupuncture at ST-36 induces dual effects, either stimulatory or inhibitory, on gastric motility. The stimulatory effects are mediated in part via vagal efferent and opioid pathways.

Routine intracranial pressure monitoring in a countryside university hospital

Intracranial pressure monitoring has become critical for the adequate management of patients with severe head injury in recent years. Several other recommendations for intracranial pressure monitoring have also been described, specially for patients with subarachnoid hemorrhage with ventricular enlargement, and spontaneous intracerebral hematomas. The immediate postoperative period of elective surgeries that require brain retraction is another instance where intracranial pressure monitoring could provide useful informations to optimize outcome. Expensive methods make it almost prohibitive to smaller centers in our Country.We describe our protocol of routine intracranial pressure monitoring using an intraventricular catheter connected to an external strain gauge transducer adapted to an ordinary invasive pressure monitor, in a countryside university hospital, and analyze the data of intracranial pressure and cerebral perfusion pressure obtained with regards to outcome and also investigate the more common complications of the method.We conclude that intracranial pressure monitoring could be safely applied at a low cost to improve the management of those patients.

Effects of body position on intracranial and cerebral perfusion pressures in isoflurane-anesthetized horses

Inhalant anesthetics may interfere with normal cerebrovascular autoregulation. It was, therefore, hypothesized that intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in isoflurane-anesthetized horses would be especially sensitive to body and head position because of the potential for large hydrostatic gradients between the brain and heart in this species. Anesthesia was induced and maintained in six clinically healthy, unmedicated geldings with 1.57% isoflurane in O2; mechanical ventilation was used to maintain normocapnia. ICP was measured by using a subarachnoid strain-gauge transducer. Blood gases and carotid arterial, right atrial, and airway pressures were also measured. Five body positions were studied in semirandomized order: dorsal recumbency (DR) with head down (HD), DR with head level (HL), lateral recumbency (LR), sternal recumbency (SR) with HL, and SR with head up (HU). Data were analyzed by using paired t-tests. ICP and CPP values, respectively, are as follows (means ± SD): 36 ± 4 and 55 ± 18 mmHg (DR-HD); 34 ± 6 and 51 ± 32 mmHg (DR-HL); 24 ± 5 and 48 ± 4 mmHg (LR); 19 ± 11 and 87 ± 12 mmHg (SR-HL); and −14 ± 7 and 71 ± 10 mmHg (SR-HU). Significant differences were found among all positions, except for SR-HL vs. LR. Significant increases in CPP were observed only in sternal positions. In conclusion, ICP in isoflurane-anesthetized horses changes inversely with the brain-to-heart hydrostatic gradient. DR may also cause increases in ICP, irrespective of head position.