Load Drop Research Articles

EFFECTS OF GLYCOSYLATED HEMOGLOBIN LEVEL ON BLOOD PRESSURE VARIABILITY IN HYPERTENSIVE PATIENTS

Objective: To investigate the effect of glycosylated hemoglobin (HbA1c) levels on blood pressure variability in hypertensive patients. Design and method: From September 2018 to April 2019, in the Xiangya Hospital of Central South University, 429 case of hypertensive patients with complete basic information, medical records, HbA1c measures and other biochemical indicators, as well as the 24-hour ambulatory blood pressure result were enroll in and divided into two groups (119 in the high HbA1c group with HbA1c more than 6.1 mg/dl and 310 in the normal HbA1c group with HbA1c less than 6.1 mg/dl). The blood variability, night drop rate, and fluctuations were compared between the two groups. Multivariate logistic regression analysis and Pearson correlation analysis were used to explore the relationship between HbA1c level and blood pressure variability. Results: In hypertensive patients, the level of systolic and diastolic pressure during 24-hour, daytime, nighttime and the proportion of non-dipping blood pressure in the high HbA1c group was higher than that in the normal HbA1c group (p < 0.05); There was no significant difference between the two groups in blood pressure load, variability, and nocturnal blood pressure drop rate (p > 0.05).Multivariate logistic regression analysis showed that nocturnal mean systolic blood pressure was a risk factor for increased HbA1c levels, with OR (95% CI) of 1.031 (1.017 to 1.045). Pearson correlation analysis implied that the level of HbA1c was positively correlated with the maximum, the minimum and the average value of 24-hour systolic pressure and mean systolic pressure of daytime and nighttime (r = 0.131, 0.129, 0.155, 0.151, 0.164; p < 0.05). Further analysis of grade 3 hypertensive patients, the high HbA1c group of had the higher value of night systolic pressure load and non-dipping blood pressure ratio. Multivariate logistic regression analysis showed that the mean nocturnal systolic pressure was a risk factor for elevated HbA1c levels, with OR (95% CI) being 3.774 (1.086 to 13.117). Conclusions: HbA1c is closely related to hypertension (especially systolic blood pressure). In the grade 3 hypertensive patients, the elevated HbA1c might increase the value of the nocturnal systolic blood pressure load.

Manufacturing Optimization and Experimental Investigation of Ex-situ Core-shell Particles Toughened Carbon/Elium® Thermoplastic Composites

Current research investigates the effect of the core-shell (C/SH) particles in composites manufactured using novel thermoplastic Elium® resin and carbon fiber reinforcement of different areal weights, 200 gsm and 400 gsm bi-angle non-crimp carbon fabrics (NCCFs). The core-shell particles were activated using the ex-situ methodology which involves the activation of particles before the Resin transfer molding (RTM) injection process. Recommended particle activation parameters are established after carrying out a detailed microscopic study to understand the melting and flattening behavior of these particles. Static indentation and damping attributes are studied to understand the influence of C/SH particles added novel carbon/Elium® composite in improving the out-of plane properties and dynamic mechanical attributes respectively. The interply regions were also toughened with the addition of 1% core-shell particles and the intensity of load drop has reduced by 20% while comparing the thick and thin ply NCCF/Elium® composites. Microscopic examination has shown that the core-shell particles helped to spread the damage evenly throughout the specimen and absorbed more energy during the static-indentation. Loss factor or damping for thick ply Elium® composite and thin ply epoxy composite is increased by 19% and 16.4% with the addition of 5% and 1% C/SH particles respectively. The underlying reasons for improvement offered by C/SH particles in quasi-static impact and dynamic mechanical tests are also deliberated in this paper.

Glass/Caryota urens hybridized fibre-reinforced nanoclay/SiC toughened epoxy hybrid composite: mechanical, drop load impact, hydrophobicity and fatigue behaviour

Glass/Caryota urens hybridized fibre-reinforced nanoclay/SiC toughened epoxy hybrid composites were prepared and characterized for its mechanical, drop load impact toughness, hydrophobicity, and fatigue behaviour. The rapidly increasing demand in polymer matrix composites proportionally increasing the environmental pollution and now this factor is a prime concern for all researchers worldwide. Thus, this research study is aimed to prepare and investigate the natural fibre-based polymer matrix composites by keeping the environmental factors in consideration. Replacing the synthetic fibres completely by natural fibre also not a great development since, the natural fibres are inferior in useful properties. Thus, in this present investigation, a hybrid form of glass-Caryota urens fibre was introduce as primary reinforcement for nanoclay-SiC toughened epoxy resin matrix. The mechanical and drop load impact results revealed that the addition of nanoclay and SiC into the epoxy resin improved the toughness together with glass-Caryota urens hybrid fibre. Moreover the addition of nanoclay and Caryota urens fibre in epoxy resin matrix improved the fatigue life cycle up to 55,182 for 50% of ultimate tensile stress. The hydrophobicity of silane-treated reinforcements gives marginal loss in water absorption compared to bare epoxy resin. These properties improved hybrid fibre epoxy composites could be used in many engineering applications.

VVER-1000/V446 spent fuel pool risk assessment and support through portable mitigating equipment

The Spent Fuel Pool (SFP) accident at the Fukushima Daiichi unit 4 demonstrated the need for identifying and analyzing possible accident sequences and subsequent application of severe accident mitigating systems in LWR (Light Water Reactor) SFPs. In this study, Level 1 Probabilistic Safety Assessment (PSA) is applied to evaluate the Fuel Damage Frequency (FDF) in SFP of Bushehr Nuclear Power Plant unit-1 (BNPP-1). This paper specifically focuses on assessing the SFP risk using Portable Mitigating Equipment (PME) including a reliable robust Portable Diesel Generator (PDG), a Portable Diesel Pump (PDP), and an SFP-spray system proposed to maintain steady decay heat removal. PME is the recommended equipment proposed by IAEA -following the Fukushima disaster- to mitigate accident consequences. In this study, the fault/event trees have been applied to conduct PSA using the SAPHIRE code. The results indicate that the most dominant Initiating Events (IEs) in the reference plant are the Loss of Offsite Power (LOOP) and Loss of Service Water (LOSW), both simultaneously affecting the reactor core and the SFP. There is a significant decrease in calculated FDF – after implementing PDG and PDP- in respect of the reference plant from 3.086E to 6 to 2.166E−7 in the normal storage mode. Heavy load drop, which is a low probability/high consequence IE, becomes crucially important in cases where PME is employed as it directly leads to fuel damage. It is expected that the analyses set forth here would provide efficient guidelines and insights into the strengths and weaknesses inherent in the design and operation of SFP in VVER-1000/V-446 nuclear power plant.

Aerothermal Optimization of Bladeless Turbines

Abstract The harnessing of mechanical power from supersonic flows is constrained by physical limitations and substantial aerodynamic losses. Bladeless axial turbines are a viable alternative to extract power in such harsh conditions without restricting the operating conditions. In this paper, we present a shape optimization of the wavy surface of bladeless turbines to maximize the power extraction, while minimizing convective heat flux and pressure losses. First, a baseline geometry was defined and an experimental campaign was carried out on the baseline wavy surface of the bladeless turbine at supersonic conditions. Pressure, heat flux, and skin friction measurements were compared with the Reynolds averaged Navier–Stokes results. Afterward, an evaluation routine which consisted of the geometry and grid generation, solving, and postprocessing was implemented within a multi-objective optimization routine to maximize the pressure force and minimize heat flux and pressure loss. Finally, a three-dimensional assessment in terms of power, heat load, and pressure drop was performed for the best performing geometry with the commercial solver cfd++ of Metacomp.

Method for determining the loads on the deflection module of the push-the-bit rotary steerable system

The article presents a method for calculating the loads on the blades - elements of the deflecting module of the push-the-bit rotary steerable system for directional drilling of oil and gas wells, affecting its reliability. It is shown that the reliability of rotary steerable systems is of particular importance as the development of unconventional oil fields expands - a highcost process that increases attention to specific factors of reliability of drilling equipment. A feature of the method for calculating the loads on the deflecting blades proposed by the authors is the representation of the rotary steerable system as an absolutely elastic rod, which is acted upon by a complex of forces arising from the directional wells with horizontal wavy segments. As a result of calculations, conditions were determined under which the interaction of forces acting on the deflecting blades will create a load close to the maximum permissible values, which increases the risk of failure of the entire bottomhole assembly of the rotary steerable system. The key condition was the change in the drilling segments of directional wells from ascending to descending when drilling a horizontal section with a wave profile, as a result of which there is a multiple load drop on the deflecting blades. Based on the calculated data, with an increase in the axial load, it is recommended to adjust the drilling mode to reduce the risk of failure of the push-the-bit rotary steerable system.

Residential and commercial UPS User's contribution to load shedding and possible solutions using renewable energy

Developing countries are facing electrical energy shortage problems. These nations are adopting load shedding to protect their national grids from instabilities. In this research, load shedding is analyzed where customers opt for the use of uninterrupted power supplies (UPS) and store energy in batteries. It is found that Pakistan has wasted 7117 GWh of energy by charging and discharging the batteries of UPS by 26, 201, 910 residential and commercial customers of the country in 2018. The energy deficit of Pakistan can be reduced from 8.7% to just 1.5% by removing all UPS from the national grid. Several renewable alternatives such as photovoltaic (PV) systems, concentrated solar power plants, pump-hydro on dams, floating PV systems, wind turbines, and PV energy import from the Middle East have been suggested. Analytic hierarchy process is used for the selection of best city and best lake for PV and floating PV system respectively based on multivariable criteria. Pakistan overcame the gap between the electrical load demand and capability in 2019. A reduction of 77% in load shedding in Pakistan resulted in a dipping of load peak of 26 GW in 2018 to 25 GW in 2019. This drop-in load in 2019 is a direct result of the removal of 77% of UPS from the national grid. India, Sri Lanka, Nepal, and other developing countries can use this analysis to enhance their power systems.

Dynamics of SARS-CoV-2 shedding in the respiratory tract depends on the severity of disease in COVID-19 patients

A fraction of COVID-19 patients progress to a severe disease manifestation with respiratory failure and the necessity of mechanical ventilation. Identifying patients at risk is critical for optimised care and early therapeutic interventions. We investigated the dynamics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) shedding relative to disease severity.We analysed nasopharyngeal and tracheal shedding of SARS-CoV-2 in 92 patients with diagnosed COVID-19. Upon admission, standardised nasopharyngeal swab or sputum samples were collected. If patients were mechanically ventilated, endotracheal aspirate samples were additionally obtained. Viral shedding was quantified by real-time PCR detection of SARS-CoV-2 RNA.45% (41 out of 92) of COVID-19 patients had a severe disease course with the need for mechanical ventilation (severe group). At week 1, the initial viral shedding determined from nasopharyngeal swabs showed no significant difference between nonsevere and severe cases. At week 2, a difference could be observed as the viral shedding remained elevated in severely ill patients. A time-course of C-reactive protein, interleukin-6 and procalcitonin revealed an even more protracted inflammatory response following the delayed drop of virus shedding load in severely ill patients. A significant proportion (47.8%) of patients showed evidence of prolonged viral shedding (>17 days), which was associated with severe disease courses (73.2%).We report that viral shedding does not differ significantly between severe and nonsevere COVID-19 cases upon admission to the hospital. Elevated SARS-CoV-2 shedding in the second week of hospitalisation, a systemic inflammatory reaction peaking between the second and third week, and prolonged viral shedding are associated with a more severe disease course.

Chloride diffusivity and mechanical performance of UHPC with hybrid fibers under heat treatment regime

Steel fibers are an inseparable part of ultra high performance concretes (UHPC). The effects of steel fibers have been widely studied in recent years; however, the hybridization of steel fiber with different types of fibers and their effect on the properties of UHPC has not been completely investigated. In addition, under thermal treatment, which is a common way for curing UHPC elements, the use of hybrid fibers may change the concrete characteristics. In this paper, mixtures containing different types of fibers in the hybrid forms were produced and the specimens were cured under normal and heat curing conditions. To characterize the effect of hybrid fibers on UHPC mixes under different curing regimes, the workability, compressive strength, flexural parameters (including first crack strength, module of rupture, load-deflection curves and toughness index) and scanning electron microscope (SEM) microstructural analyses were investigated. The results revealed that the concrete mix with 2.5 % mono fiber had higher flexural performance than the hybrid mixes. However, the use of steel fiber with the volume fraction of 1.5 % was more effective in improving the compressive strength. Higher flexural load-bearing capacity was observed for the hybrid mixes with macro fibers of Barchip and Kortta. The UHP-FRCs containing Barchip and Kortta fibers, due to the permeable internal structure, had lower chloride resistance than the 2.5 % of steel fiber concrete. In addition, the chloride migration coefficients of the hybrid mixtures with the glass, carbon and polypropylene fibers were about 5 times higher than those of the mix with 1.5 % steel fiber. Compared with normal curing condition, the load drop after cracking was more visible for the mixes cured under heat curing, which could be limited by using high-volume steel fiber and hybrid micro fibers. Furthermore, applying thermal treatment for curing concrete mixes led to lower chloride ion penetration; the enhancement was more pronounced for the hybrid mixes with micro fibers of glass, carbon and polypropylene.

Making security glazing from modified TEMPO oxidized nanofibers and poly vinylbutyral

Safety glazing is a type of laminated glazing that holds together when shattered, due to the presence of an interlayer usually made of polyvinyl butyral (PVB). It is widely used in industrial application where the glazing could fall, or become a projectile to avoid serious injuries to humans after an impact with a foreign object. To replace the PVB, we have developed a modified cellulose nanofibers (NFC) by grafting poly(glycidyl methacrylate) with glycerol addition. This modification has improved the NFC pure performance as well as their compatibility with polar polymers. Therefore, this study reports the preparation and characterization of laminated glazing with composites of PVB reinforced with 40, 50 and 70% by weight of modified NFC. Composites interlayers are very transparent (up to 93% light transmission) with an interesting light character (up to 18.72% weight loss) in comparison to a PVB interlayer only. The chosen laminated glazing have been characterized by quasi-static (three-point bending) and dynamic impact loading (drop weight test). The quasi-static show the force–displacement curves of glazing while the dynamic testing give the energy absorption capability and maximum impact force. In our testing, the glazing with modified NFC have shown increased mechanical properties. Moreover, the laminated glazing made with an interlayer reinforced with 40% NFC exhibits the highest impact properties with a maximum force at break of 36,270 N and 24.81 J of absorbed energy. This study has shown that the modified NFC is indeed a lighter and environment-friendlier alternative for laminated glazing.

Effects of corrosion level and inhibitor on pullout behavior of deformed steel fiber embedded in high performance concrete

This study investigated effects of corrosion level and inhibitor on the pullout behavior of deformed steel fibers. Two types of deformed (hooked and twisted) steel fiber, were embedded in two different matrices (28 MPa and 84 MPa). The calcium nitrite corrosion inhibitor (CNI) was added at a volume of 25 l/m3. An impressed current technique was used to generate different corrosion levels in the steel fibers. As the corrosion level increased, the pullout resistance of deformed steel fibers increased by maintaining fiber pullout mode and even slip hardening behavior. However, beyond a certain corrosion level, the pullout resistance was deteriorated due to fiber breakage and a sudden drop of pullout load at very small slip. The maximum corrosion level of deformed steel fibers should be limited to 12% for ensuring fiber bridging capacity at the composite level. The addition of CNI was beneficial for maintaining fiber pullout mode even at high corrosion level. By adding CNI, the maximum corrosion level of deformed steel fiber could be limited to 18%.

Mechanical Strength Characterization of Plastic Fiber Reinforced Cement Concrete Composites

The reinforcing efficiency of plastic fibers obtained from shredded plastic waste was tested in plain concrete mixes and experimentally verified in this study. Plastic fibers up to 0.15% Vf were added to the design concrete mix to assess the fiber effectiveness in terms of improved load carrying capability of various plastic fiber incorporated concrete composites. The effects of plastic fibers distributed homogenously in the entire depth of concrete and confined in the tension zone were evaluated in flexural bending properties. Mechanical strength properties were evaluated for two different types of concrete containing (i) plastic fibers added homogenously throughout the entire depth of concrete and (ii) the plastic fibers confined in the tension zone only. Flexural bending parameters such as toughness, residual strength, crack width, post-peak drop load resistance, and fiber performance index of various plastic fiber substituted concrete mixes were tested in compressive and flexural bending to assess the fiber reinforcing efficiency. Test results indicated that the plastic fibers added in tension zone confinement exhibited higher flexural strength (5.26 N/mm2) improvements compared to homogeneously distributed concrete systems. Flexural bending characteristics in terms of absolute toughness and post peak strain softening were found to be appreciably higher (132%) in tension zone confined plastic fiber concretes compared to homogeneous fiber concrete systems.

Validation of loop-mediated isothermal amplification for the detection of Loa loa infection in Chrysops spp in experimental and natural field conditions

BackgroundThe mass drug administration of ivermectin for onchocerciasis control has contributed to a significant drop in Loa loa microfilaria loads in humans that has, in turn, led to reduction of infection levels in Chrysops vectors. Accurate parasite detection is essential for assessing loiasis transmission as it provides a potential alternative or indirect strategy for addressing the problem of co-endemic loiasis and lymphatic filariasis through the Onchocerciasis Elimination Programme and it further reflects the true magnitude of the loiasis problem as excess human mortality has been reported to be associated with the disease. Although microscopy is the gold standard for detecting the infection, the sensitivity of this method is compromised when the intensity of infection is low. The loop-mediated isothermal amplification (LAMP) assay of parasite DNA is an alternative method for detecting infection which offers operational simplicity, rapidity and versatility of visual readout options. The aim of this study was to validate the Loa loa LAMP assay for the detection of infected Chrysops spp. under experimental and natural field conditions.MethodsTwo sets of 18 flies were fed on volunteers with either a low (< 10 mf/ml) or high (> 30,000mf/ml) microfilarial load. The fed flies were maintained under laboratory conditions for 14 days and then analysed using LAMP for the detection of L. loa infection. In addition, a total of 9270 flies were collected from the north-west, east, and south-west regions (SW 1 and 2) of Cameroon using sweep nets and subjected to microscopy (7841 flies) and LAMP (1291 flies plus 138 nulliparous flies) analyses.ResultsThe LAMP assay successfully detected parasites in Chrysops fed on volunteers with both low and high microfilariaemic loads. Field validation and surveillance studies revealed LAMP-based infection rates ranging from 0.5 to 31.6%, with the lowest levels in SW 2 and the highest infection rates in SW 1. The LAMP assay detected significantly higher infection rates than microscopy in four of the five study sites.ConclusionThis study demonstrated the potential of LAMP as a simple surveillance tool. It was found to be more sensitive than microscopy for the detection of experimental and natural L. loa infections in Chrysops vectors.Graphical

Design of friction stir welding for butt joining of aluminum to steel of dissimilar thickness: heat treatment and fracture behavior

A 5-mm-thick aluminum sheet (Al) was successfully welded by friction stir welding (FSW) to a 3-mm-thick carbon steel (St) in a butt configuration. For this purpose, a new joint design was used where a support plate was employed under the St part and an insert layer made of steel was used between the support plate and the Al part. A stationary shoulder was also considered in the joint design. After welding, an intermetallic compound (IMC) layer of FeAl with less than 3 μm thickness was obtained along the bond line. The joint was then tested in tensile loading conditions. An abrupt load drop was observed during the test, which was due to crack propagation from pre-existed cracks in the IMC layer. A cohesion zone model (CZM) was used to simulate the fracture behavior of the joints and obtain the fracture energy of the IMC layer. Based on the CZM results, the fracture energy of the as-welded and heat-treated joints was obtained as 0.2 and 0.13 N/mm, respectively. A comprehensive analysis of the joints showed that the irregularities and fragments of steel in the IMC layer delay the propagation of cracks. Consequently, a higher fracture energy is obtained with respect to the heat-treated joint, in which a continuous IMC layer exists.

Extremely Low Cycle Fatigue Failure Behavior of Box-column to I-beam Welded Joints

In this paper, cyclic loading tests are carried out to study the extremely-low-cycle fatigue (ELCF) failure behavior of the beam-to-column welded joints of steel structures subjected to severe seismic excitation. Firstly, the fatigue crack evolution and local strain of the weld zone obtained from experiments are adopted to investigate ELCF failure behavior for steel structures. In these experiments, three large scale specimens of box-column to I-beam connection are controlled by different cycle displacement ranges greater than the yield displacement. Secondly, the crack initiation and propagation law as well as the damage and deterioration mechanism are examined; then, the preliminary criterion for crack initiation for the box-column joint is proposed. Finally, failure characteristics and strain distribution of the box-column joint are analyzed. This study shows that the ELCF failure of the box-column to the I-beam joint is multiaxial and nonproportional. Based on the crack initiation and propagation along the thickness direction of the beam flange, the crack macro-penetration mode can be divided into two categories, i.e., standard failure mode and mixed failure mode. Moreover, load drop, change rate of load drop, and loading amplitude are key factors of the damage mechanism.

Test on mechanical behavior of SRC L-shaped columns under combined torsion and bending moment

Investigations of the seismic behavior of steel reinforced concrete L-shaped columns under constant axial compression and cycled bending-shear-torsion load were performed. Six specimens, which considered two parameters, i.e., the moment ratio of torsion to bending (γ) and the aspect ratio (column length-to-depth ratio, ϕ), were prepared for the experiment. In this study, the failure process, torsion-displacement hysteresis curves, and flexure-displacement hysteresis curves were obtained. The failure characteristics, mechanical behavior of specimens such as the failure patterns, hysteresis curves, rigidity degradation, ductility and energy dissipation, are analyzed. The experimental research indicated that the major failures of the specimens were bending failure, bending-shear failure and bending-torsion failure as the moment ratio of torsion to bending (γ) increased. The torsion-displacement hysteresis curves were pinched in the middle, formed a slip platform, and the phenomenon of “load drop” occurred after the peak load. The bending-displacement hysteresis curves were plump, which showed that bending capacity of the specimen was better than its torsion capacity. Additionally, the energy dissipation of the specimen was dominated by torsion in the early stage and ultimately governed by the bending moment in the later phase. Test results also indicated that the displacement ductility coefficient and interstory rotation angle of the failure point were less than 3.0 and 1/50, respectively, which means the test specimen performance does not meet the requirement of the Chinese Code for Seismic Design of Buildings (GB 50011–2014) in this respect.

Influence of hepatitis B virus co-infection on virological and immunological response to antiretroviral treatment among HIV patients attending comprehensive care clinics in Makueni County, Kenya.

Introductionthe effect of hepatitis B virus (HBV) infection on the natural history of human immunodeficiency virus (HIV) disease remains uncertain. Therefore, this study was conducted to determine the association of HBV co-infections with CD4 count and viral load levels in response to antiretroviral treatment among HIV patients attending comprehensive care clinics in Makueni County (Kenya).Methodsthis was a prospective case-control study among patients seeking HIV services in three hospitals of Makueni County (Kenya). Newly diagnosed HIV mono-infected patients (controls) and HIV/HBV co-infected (cases), 18 years and above who had not started antiretrovirals (ARVs) participated. A total of 258 patients gave informed consent and participated. HIV mono-infected (controls) produced 129 while HIV/HBV (cases) gave 129 participants. P-values ≤ 0.05 were considered significant.Resultsthe majority (164, 63%) of the study participants were females for both arms of the study. The mean age of the participants was 31±0.402 years and majority of them were between the age of 26-30years old. At the beginning and end of the study the mean viral load for HIV/HBV co-infected individuals was (30169 and 1731) copies/ml while that of CD4 count was (327 and 459) cells/ul, and that of HIV mono-infected was (21860 and 1689) copies/ml and CD4 count of (421 and 437) cells/ul respectively. After enrolling them into antiretroviral therapy (ART) treatment and after six months of follow-up there was significant drop in viral load and significant increase in CD4 count for both groups at p<0.001 using logistic regression.ConclusionHIV patients co-infected with hepatitis B virus had high viral load and low CD4 count compared to HIV monoinfected patients however with introduction of ARVs there was improvement in both groups with the highest noticed among the HIV/HBV co-infected patients.

Investigation of Pop-in Formation Mechanism in Fracture Toughness Test of Welded Joint and Revision of Acceptance Criteria

A pop-in is a small, arrested brittle crack occurs during a fracture toughness test. This is one of the important factors of the CTOD assessment of a welded joint because the fracture toughness of a material differs by the significance of the pop-in. The current standard of the pop-in is said to be too conservative because of the reasons below; the absence of the test specimen which ensures pop-ins, and the difference of the loading mode between the CTOD test and the real structures. The objective of this study is to investigate the mechanism of the pop-in formation and to improve the pop-in acceptance criteria. Firstly, experiments are carried out with the “brittle bead specimen” which is a welded specimen that artificially represents the local brittle zone so that the pop-in stably occurs. From the result of the experiment, the standard of the load drop ratio of the pop-in can be set as 10% from the current 5%. Next, the finite element method analysis is performed to see the difference of the loading mode of the bending and tensile. From the result of the FEM analysis, it is suggested that the previous research of the pop-in is incorrect and the new model of the pop-in formation with the parameter of the width of the local brittle zone is proposed.

К ВОПРОСУ О ПЕРЕРАСПРЕДЕЛЕНИИ НАПРЯЖЕНИЙ В ВЕРТИКАЛЬНЫХ НЕСУЩИХ ЖЕЛЕЗОБЕТОННЫХ КОНСТРУКЦИЯХ МНОГОЭТАЖНЫХ ЗДАНИЙ

In this paper, resistance the shear lintels in multi-story buildings is considered, since the main static purpose of vertical butt joints in the form of lintels is to ensure the perception of shear forces arising from the joint operation of the mating walls. The object of the study was a fragment of a monolithic building, the thickness of the walls of which was 300 mm, and the height of the building was 12 floors. As a result of the conducted numerical studies, the stress-strain state of the vertical load-bearing structures of monolithic buildings and the shear deformations along all the lintels along the height of the building were determined. It was found that some of the lintels are in the elastic stage of operation due to a low level of shearing forces. A number of building lintels connecting vertical structures with a significant vertical load drop are in the plastic stage of work. The results of stress redistribution, given in this article, can be used when calculating the bearing systems of monolithic buildings, taking into account the nonlinear compliance of shear bonds.

ПРОЕКТУВАННЯ БАГАТОФУНКЦІОНАЛЬНОГО БПЛА РОТОРНОГО ТИПУ НА БАЗІ ПРОШИВКИ ARDUPILOT

In this work, a multifunctional rotor-type UAV (hexacopter) was designed based on the Arducopter ver.4.0.7 firmware for FMUv3 devices. Experimental tuning of the firmware parameters for a given UAV geometry, its weight, propeller group, flight stability in a gusty wind for navigation modes has been performed. It is shown that this flight controller can use all the documented features of the Ardupilot firmware, unlike the Pixhawk1 1M. Experimentally, on the basis of numerous flights, it was revealed that firmware using a mathematical apparatus based on the extended Kalman filter (Arducopter 4.0.7) gives better flight results in navigation modes than firmware based on the use of a complimentary filter (INAV, Betaflight - rescue mode). The possibility of controlling additional equipment using a flight controller is shown using the example of dropping a load at a given point of the trajectory. The results of telemetry were obtained during the automatic flight of the hexacopter along a given trajectory based on the installed sensors. It is shown how, using the ground station software, it is possible to obtain two-dimensional and three-dimensional graphical representations of telemetry data for analyzing the flight of a copter with its subsequent fine tuning. The possibility of constructing and constructing a three-dimensional trajectory of the UAV flight according to telemetry data using the Google Earth program has been studied. Considered the fine tuning of UAV flight modes using the Ardupilot firmware parameters. The parameters are identified that are basic for ensuring maximum flight stability in abruptly changing conditions, for example, during sudden braking, maneuvers, gusty wind. The range of variation of these parameters and their values have been determined experimentally. The parameters of the PID controller were tuned to ensure a smooth and stable flight in navigation modes. In work with the use of a servo drive, a load dropping device has been designed, which can be triggered automatically when flying along a trajectory, and when commanding from the control panel when approaching a given point, which is visually viewed using the Mission Planner.