The criteria for the rejection of ropes of Passenger cable cars are considered, the main defects of load-bearing, traction and load-bearing cables, possible causes of their occurrence and the ...criteria for rejection are described. The theoretical substantiation of defects associated with plastic deformations of the rope wire (extrusion of wires, stratification, twisting of the rope, kinks, breaks, basket shape) is given. The methods of monitoring the state of ropes in the process of operation of passenger cable cars are considered. Recommendations are given to improve the level of security by using remote monitoring systems based on modern digital information technologies. The criteria for rejecting the ropes of passenger cable cars are proposed: according to the undulation, wear and breakage of the outer wires of the ropes, which are absent in the current Federal Norms and rules «Rules for the safety of passenger cable cars and funiculars».
In this article, we study the decision-making criteria that business angels (BAs) adopt when screening business opportunities in the different assessment phases (pre-screening, screening and due ...diligence). We exploit an original dataset of 1942 ventures that sought angel investment from 2008 to 2014 from the members of Italian Angels for Growth (IAG). Results have shown that the emphasis that BAs place on rejection criteria and contact channels varies along the three considered stages of the investment process. In particular, we found that business proposals brought to the attention of BAs by venture capitalists are more likely to get through the pre-screening stage, suggesting an important quality certification role played by venture capitalists. Moreover, at the screening stage (in comparison with the pre-screening stage), proposals are rejected more often for reasons related to the characteristics of the entrepreneur and management team and less often for the lack of business innovativeness. Finally, business proposals showing lower levels of profitability are more likely to be rejected after the due diligence.
How do business angels assess a prospective entrepreneurial firm when they make an investment decision? This article examines a central question that informal venture capitalists have been struggling ...with for decades: What early stage decision making criteria do investors define and apply to reduce the volume of potential deals to a more manageable size? Based on semi-structured interviews with business angels in an emerging market, we show that investors are focused on the industry structure and product features, on the other side, our results also suggest a very strong support for the personality of the entrepreneur and management team. More specifically, entrepreneur trustworthiness is an essential element affecting an investor's decision to close a deal. Business angels set requirements in terms of the entrepreneur's equity stake in the start-up and monitoring tools to prevent the failure of investee firms. Our findings suggest that if there are warning signs that the project is in an existential crisis, most of the investors will reject their participation. We believe that our empirical results support both researchers and practitioners to establish a better understanding between the well-developed financial theories and the underresearched informal venture capital market in a Central and Eastern European country.
Fluvial terraces in the upper Hunter catchment, southeastern Australia provide a long-term record of river activity in response to climate change in the late Quaternary. Single-grain optically ...stimulated luminescence (OSL) dating of quartz was applied in this study to investigate the timing of the formation of three fluvial terraces in the upper Hunter catchment. A detailed examination of luminescence properties of individual quartz grains revealed some correlation between their OSL decay rates, intrinsic brightness and dose saturation characteristics. Some quartz grains containing a higher proportion of non-fast components exhibit low brightness in OSL signals and high dose saturation levels. Some grains with slow OSL decays pass the standard rejection criteria, but are likely to yield underestimated equivalent doses (Des) because of a higher contribution of non-fast components, which are shown to have low thermal stability. Different rejection criteria, including the fast ratio, the dose saturation level and the OSL sensitivity criteria, were tested on the single-grain De results. Application of a fast ratio rejection criterion is able to successfully identify thermally unstable grains. A new rejection criterion based on dose saturation property was also applied to improve the age of one sample with a large De. Our dating results identify multiple phases of river valley aggradation in the upper Hunter catchment since late Marine Isotope Stage (MIS) 6; at ∼ 138 ka, ∼90–94 ka, ∼65 ka, ∼26 ka and ∼18 ka. The aggradational episodes of the terraces in the upper Hunter catchment are correlated with glacial or stadial periods since MIS 6. These phases of valley-floor aggradation are inferred to be a function of increased sediment supply during the cold periods resulting from strong periglacial activities in the adjacent Australian highlands.
•We optically dated three fluvial terraces in the upper Hunter catchment, SE Australia.•We found a linkage between multiple luminescence properties for single quartz grains.•Application of additional SG rejection criteria can improve the SG OSL dating results.•Terraces in the upper Hunter catchment aggraded in glacial or stadial episodes.•Terrace aggradation may result from strong periglacial activities during cold periods.
Mathematical model of splicing of steel cable Korotkiy, Anatoliy A.; Marchenko, Edward V.; Panfilov, Alexey V.
Nauchno-tekhnicheskiĭ vestnik Bri͡a︡nskogo gosudarstvennogo universiteta,
09/2019, Volume:
5, Issue:
3
Journal Article
Peer reviewed
Open access
he article presents materials on the study of mathematical modeling of jointing (splicing) of a steel rope used to transfer the traction force by friction forces. The developed mathematical model of ...jointing describes the stress-strain state of strands (wires) from quasi-static loads arising in the process of cyclic stretching and bending of the steel rope on the traction pulley, in which the resultant force in the pop-river section of the steel rope shifts relative to the central axis, causing its bending and twisting. Using experimental data, it is established that the torsion and bending of the steel rope is called the technology of jointing in the nodes where the replacement of strands occurs. It is experimentally established that defects in the area of jointing (splicing) are manifested as a result of cyclic tensile and bending loads on the pulley, which is associated with limited mobility of the strands in the nodes due to a violation of the symmetry of the cross section. When stretching and bending on the pulley, the load between the strands of the rope is distributed very unequally, which ultimately leads to its out-of-center stretching and the formation of a «wavy» defect. The mathematical model describes the process of jointing (splicing) of the steel plate, taking into account the existing technology that violates the symmetry of the cross section in the nodes, which, as a result of quasi-static loads, develops to critical values of the rejection index «waviness».
The article discusses questions of shaping honeycomb panels for turbojet engine noise insulation casings. Various types of structures and materials used for manufacturing honeycomb panels are ...presented. Samples were tested to determine mechanical characteristics. The technology of manufacturing honeycomb panels was determined by the value of relative elongation. The main rejection criteria in forming panels on bending and stretching presses were reviewed. The process of shaping honeycomb panels using computer numerical control (CNC) equipment was analyzed. Force parameters of the shaping process required for the assessment of the stress-strain state and obtaining the control program were determined. The values of the spring action were calculated for single-layer and double-layer panels using the A.A. Ilyushin unloading theorem. It was found that the springing of single-layer and two-layer panels differs due to the magnitude of the generalized rigidity. The value of springing is determined by the known height of the honeycomb panel. Designs of honeycomb panels with different positions of the middle layer along the height of the panel are given. Graphs showing the dependence of the punch radius adjusted for the value of springing on the radius of the part for various types of structures from titanium alloys and stainless steels are presented.
•Wicking of oil into paper to distinguish fresh from prolonged fried oil.•Developed semi-empirical model explains the deviations from the L–W behavior.•Specifications for an effective wicking based ...rapid test are set.
This work investigates the potential of developing a rapid test based on wicking of oil into paper for determining whether a reused frying oil is to be rejected. To achieve this goal, wicking patterns (oil penetration rate and oil front shape versus time) of both fresh and prolonged fried extra virgin olive oil are optically registered at six different paper stripes. Four of them are double-ply towel papers whereas the other two are single-ply chromatographic papers. Wicking tests are performed at 20°C and 30°C. It is shown that the type of paper affects seriously the wicking patterns. Double-ply papers present high oil penetration rates but very irregular oil front shapes whereas single-ply papers yield lower oil penetration rates but pretty flat oil fronts. Furthermore, it is found that only under certain conditions the penetration rates obey the well known Lucas–Washburn equation. A discussion is made on the phenomena that take place during wicking of oil into paper which may cause deviations from the Lucas–Washburn equation. A semi-empirical model is proposed to describe the above deviations by incorporating the effect of time evolving pore sizes.
This paper presents a novel cascade ensemble classifier system for the recognition of handwritten digits. This new system aims at attaining a very high recognition rate and a very high reliability at ...the same time, in other words, achieving an excellent recognition performance of handwritten digits. The trade-offs among recognition, error, and rejection rates of the new recognition system are analyzed. Three solutions are proposed: (i) extracting more discriminative features to attain a high recognition rate, (ii) using ensemble classifiers to suppress the error rate and (iii) employing a novel cascade system to enhance the recognition rate and to reduce the rejection rate. Based on these strategies, seven sets of discriminative features and three sets of random hybrid features are extracted and used in the different layers of the cascade recognition system. The novel gating networks (GNs) are used to congregate the confidence values of three parallel artificial neural networks (ANNs) classifiers. The weights of the GNs are trained by the genetic algorithms (GAs) to achieve the overall optimal performance. Experiments conducted on the MNIST handwritten numeral database are shown with encouraging results: a high reliability of 99.96% with minimal rejection, or a 99.59% correct recognition rate without rejection in the last cascade layer.
Continuous measurements of methane (CH₄) emissions from agricultural facilities over a period of several days are needed to assess the mitigation effectiveness of management practices. In this study, ...we examined the feasibility of using an inverse dispersion technique (backward Lagrangian Stochastic model, bLS) for obtaining 15-min averages of CH₄ emissions over a period of 5 days in the Ottawa area. Using two open-path lasers and pan-tilt scanning units, a ground level source was enclosed to measure the CH₄ emissions (Q) with any wind direction. After application of the recommended data quality criteria screening for low friction velocity and extreme atmospheric stability, the average recovery (ratio of estimates Q bLS to Q) was 1.09 with a standard deviation of 0.45. We observed a tendency in the recovery results toward underestimation during unstable stratification and overestimation during stable stratification. Using a test on developed turbulence instead of a fixed friction velocity threshold improved the accuracy of the emission estimates slightly. An additional data quality criterion based on the standard deviation output of the bLS model led to a significant improvement with a recovery of 1.00 and a standard deviation of 0.30. A strategy for averaging the resulting incomplete dataset is discussed. An assessment of the applicability of this approach to farm-size facilities led to the conclusion that this technique is suitable to determine emissions from realistic CH₄ sources, such as dairy cattle barns, continuously in order to characterize both seasonal and diurnal characteristics of CH₄ emissions.
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