Identical Sections Research Articles

Optical caustics of multiple objects in water: two vertical rods and normally incident light.

The optical caustics of the combined water menisci raised by two objects with identical circular cross sections show peculiar caustic metamorphoses known from binary gravitational lenses. We highlight their genericity and analyze the connection of the refracting interface topography and curvature landscape with the caustics' (and their images') topology.

Nonlinear Schamel–Korteweg deVries equation for a modified Noguchi nonlinear electric transmission network: Analytical circuit modeling

• Anew capacitance-voltage characteristics containing a square root nonlinearity is built and used for circuit modeling of a modified Noguchi nonlinear transmission network. • The perturbation method in the continuum limit is used to show that the weakly modulated waves propagating in the our model can be governed by the nonlinear Schamel-Korteweg-de Vries equation. • New soliton and periodic solutions of the Schamel-Korteweg-de Vries equation are derived and used to investigate the dependency of the characteristics of parameters of bright soliton and periodic signals on the network parameters. A modified Noguchi nonlinear electric transmission network that consists of a large number of identical sections is theoretically studied in the present work. A new capacitance-voltage (C-V) characteristics of the diodes containing a square root nonlinearity is introduced and used to show that in the continuum limit, the voltage for the transmission line is described by the Schamel Korteweg de Vries (S-KdV) equation. The dependency of the characteristics of modulated wave parameters on our nonlinear electric transmission network are shown in the work. The results found in this paper are of great interest and can be exploited in other areas of physics such as in plasma physics .

Design of a Practical Underwater Sensor Network for Offshore Fish Farm Cages.

In this paper, we present the design of a practical underwater sensor network for offshore fish farm cages. An overview of the current structure of an offshore fish farm, applied sensor network solutions, and their weaknesses are given. A mixed wireless–wired approach is proposed to mitigate the problem of wire breakage in underwater wired sensor networks. The approach is based on the serial arrangement of identical sections with wired and wireless interconnections areas. Wireless section alleviates underwater maintenance operations when cages are damaged. The analytical model of the proposed solution is studied in terms of maximum power transfer efficiency and the general formulas of the current in their transmitting antennas and sensor nodes are provided. Subsequently, based on simulations, the effects of parasitic resistance across the network are evaluated. A practical underwater sensor network to reach the 30 m depth with sensor nodes distanced 6 m is used to determine the proposal compliance with the ISO 11784/11785 HDX standard in its normal operation. Taking into account the cable breakage scenario, the results from experiments demonstrate the robustness of the proposed approach to keep running the sensor nodes that are located before the short circuit. Sensor node run time is reduced only 4.07% at most using standard values when a cable breakage occurs at the second deepest section.

Engineering rogue waves with quintic nonlinearity and nonlinear dispersion effects in a modified Nogochi nonlinear electric transmission network.

A one-dimensional modified Nogochi nonlinear electric transmission network with dispersive elements that consist of a large number of identical sections is theoretically studied in the present paper. The first-order nonautonomous rogue waves with quintic nonlinearity and nonlinear dispersion effects in this network are predicted and analyzed using the cubic-quintic nonlinear Schrödinger (CQ-NLS) equation with a cubic nonlinear derivative term. The results show that, in the semidiscrete limit, the voltage for the transmission network is described in some cases by the CQ-NLS equation with a derivative term that is derived employing the reductive perturbation technique. A one-parameter first-order rational solution of the derived CQ-NLS equation is presented and used to investigate analytically the dependency of the characteristics of the first-order rouge wave parameters on the electric transmission network under consideration. Our results show that when we change the quintic nonlinear and nonlinear dispersion parameter, the first-order nonautonomous rogue wave transforms into the bright-like soliton. Our results also reveal that the shape of the first-order nonautonomous rogue waves does not change when we tune the quintic nonlinear and nonlinear dispersion parameter, while the quintic nonlinear term and nonlinear dispersion effect affect the velocity of first-rogue waves and the evolution of their phase. We also show that the network parameters as well as the frequency of the carrier voltage signal can be used to manage the motion of the first-order nonautonomous rogue waves in the electrical network under consideration. Our results may help to control and manage rogue waves experimentally in electric networks.

Teleophthalmology Using Whole Slide Imaging (WSI): Clinical-Pathological Correlation Even Without Own Histological Laboratory

Telepathology has experienced enormous growth over the last two decades due to significant advances in IT and has led to the introduction of innovative solutions for digital imaging in ophthalmology. Whole Slide Imaging (WSI), where conventional glass slides are fully scanned, offers a wide range of applications, including remote (conciliary) diagnostics, second opinions, (remote) teaching and research and presentation. In addition to qualified and experienced personnel, a comparatively expensive basic equipment has so far also been an essential requirement. The focus ophthalmology at the Eye Centre in Freiburg is able to involve a de facto unlimited number of users and consulting partners (also overseas) in the digital microscopy of identical sections independent of location, device and time. This is done simply by using the internet. This procedure has proven to be very successful and opens up completely new avenues, not only for correct diagnosis (clinical-pathological correlation), but also for education and training. Preparation and distribution of further histological slides in addition to the scanned slide is not required for small specimens with scant material, for example, nor is it necessary to purchase microscopes for the participants if funds are lacking or the infrastructure is unsuitable. When dealing with transferring data, it is essential to comply with data protection regulations.

Strength enhancement of high strength steel beams by engineered cementitious composites encasement

This study proposes a method of using Polyvinyl Alcohol Engineered Cementitious Composites (PVA-ECC) encasement to provide continuous restraints along the compression flange of High Strength Steel (HSS) section so that it will reach its sectional plastic moment resistance under bending without lateral restraint. In order to demonstrate the effectiveness of the proposed method, experimental and numerical investigations were carried out to study the flexural strength of the ECC encased HSS beams (ECC-HSS beams). Six simply supported beams fabricated with identical HSS sections but with different encasement configurations were tested until failure. Flexural resistance and failure modes of the ECC-HSS beams were compared with similar bare HSS and normal concrete (NC) encased HSS beams (NC-HSS beams). It was found that when compared with the bare HSS and NC-HSS beams, a significant enhancement in flexural resistance was achieved for the ECC-HSS beams. More importantly, this study confirmed that the compressive ECC layers was crushed after the compression flanges were yielded and therefore successfully prevented the onset of lateral torsional buckling. Besides the flexural responses, the interfacial slip behaviours along the compression flange of the HSS section were also studied. Finally, a finite element (FE) model was developed and validated against the experimental results.

Collaborative learning in online business education: Evidence from a field experiment

Although online business degrees and student enrollments have increased, course quality and outcomes remain a challenge. We designed a collaborative learning activity at a large public university involving student-produced materials in an online managerial economics class. The activity included two parts: student production of a problem-solving video and rating of peer work. Students were randomly-sorted across identical class sections with and without the new activity. The findings based on final exam scores show that peer learning provides a positive impact on overall learning, and the activity also improves knowledge with respect to the topic of the video made.

A Stylometric Analysis of Ljósvetninga saga

Ljósvetninga saga is preserved in two primary versions, the A-redaction and C-redaction. These two redactions feature parallel (though not identical) sections as well as a section (chapters 13–18) which is entirely divergent. Scholars and editors have long disagreed over the question of which version of the saga is more internally consistent. Two stylistic studies by Adolfine Erichsen in 1919 and Hallvard Magerøy in 1956 arrived at opposite conclusions: the former preferring the stylistic coherence of the C-redaction and the latter preferring the A-redaction. The conclusions of these scholars reflected opposing stances on the Freeprose-Bookprose origin of the Íslendingasögur. Proponents of the Freeprose school including Knut Liestøl leveraged Erichsen’s stylistic investigation to argue that the divergent section in A-redaction should be considered a genuine oral variant, whereas proponents of the Bookprose school (including the editor of the saga’s Íslenzk fornrit edition, Björn Sigfússon) criticized the oral understanding and instead framed the divergent C-redaction section as a historical novelization of what was originally the A-redaction. The development of stylometry in recent years has provided us with a statistically-robust set of methods to interrogate the style of texts. In this article, the authors revisit the debate and present stylometric evidence to support Erichsen’s conclusion and reject Magerøy’s: the divergent section of the C-redaction has more in common with the parallel chapters and the A-redaction is likely an independent version of the text retold, possibly with recourse to oral tradition.

Сдвиговый спекл-интерферометр с квадролинзой

The paper proposes a new optical element – Quad lens, which is used as part of a shearing speckle interferometer (sherograph) to provide measurements of stress-strain states of objects simultaneously in two mutually perpendicular directions. Quad lens consists of four identical sections cut from the original round lenses and spaced from each other to form a gap. Quad lens creates four images of an object that are offset relative to the optical axis by a distance that depends on the size of the gaps between the sectors. Phase recovery from a single speckle interferogram is performed using the spatial phase shift method based on the Fourier transform. To increase the contrast of interference bands, an aperture diaphragm with four holes is installed in front of quad lens sectors, and polarizing channel isolation can be used to separate channels and reduce the influence of cross interference. Experimental results of using a speckle interferometer with quad lens for the study of microdeformation of a round membrane are presented.

Self-Packaged Balanced Bandpass Filters With Impedance Transformation Characteristic

In this article, the co-design of novel self-packaged balanced bandpass filters (BPFs) integrated with the functionality of impedance transformation is presented for the first time. The proposed design is based on a modified branch-line structure, which is composed of two different branch lines and two identical coupled-line sections. Analysis results show that the considered filters can not only achieve Chebyshev equal-ripple responses with impedance transformation properties for the differential mode (DM) but also can efficiently improve the bandwidth of the common-mode (CM) rejection with resorting to this modified branch-line structure. Furthermore, according to the specified equal-ripple fractional bandwidth (FBW), in-band return loss (RL) level, and impedance transformation ratio ${m}$ , the DM frequency response can be directly determined. Two design prototypes, the second-order balanced BPF with a 50–75- $\Omega $ ( $m= 1.5$ ) impedance transformation and the third-order one with a 50–200- $\Omega $ ( $m= 4$ ) impedance transformation, are implemented in self-packaged forms by using the multilayer liquid crystal polymer (LCP)-bonded printed circuit board (PCB) technology. Theoretical, simulated, and measured results are recorded in good agreement, well verifying the design concept.

Structural Design of Cold-formed Steel face-to-face Connected Built-up beams using Direct Strength Method

The structural behavior of cold-formed steel (CFS) built-up beams that are gaining interest in the construction industry is investigated in this study. As per the current American Iron and Steel Institute's (AISI) CFS structural members specifications (direct strength method), there are no explicit guidelines or procedures for the types of built-up sections being evaluated in this research. The present study, therefore, examines the suitability of using the current AISI design specifications for the design of CFS built-up beams. The built-up beams investigated in this study are assembled using two identical sigma sections, and interconnected face-to-face by discrete spot welding. The test parameters studied include the length of the member (L) and spacing (sl) between the interconnecting spot welds. Based on the failure modes observed in experiments, new limitations for the interconnection spacing (smax) of the face-to-face connected built-up beams that failed in distortional buckling is suggested. The design strength prediction (MDSM) for the tested built-up beams is calculated using current AISI design procedure for the purpose of verification and to extend the current design procedure for the built-up beams. The comparison between experimental tests and design predictions (MEXP vs. MDSM) indicates that the design results are unconservative and unreliable due to the incorrect failure mode prediction and overestimation of the critical elastic buckling stresses in the elastic buckling analysis which is a key input to the direct strength method of design calculations. Hence, modified design procedures and design equations were suggested for the CFS built-up beams after carrying out a comprehensive investigation on failure modes and numerical study that are vulnerable to fail in distortional buckling. It was also shown that the newly suggested procedures and equations are reliable for the design of CFS built-up beams.

Super rogue waves in coupled electric transmission lines

Coupled electric transmission lines (CETLs), which consist of a great number of identical sections, have been studied theoretically in the present paper. The super rogue wave (SRW) in CETLs is analyzed using the nonlinear Schrodinger equation. The dependence of the characteristics of the SRW parameters on CETLs is displayed in this paper. The results may be useful for exploiting or avoiding SRWs in CETLs.

Experimental Hydraulic Investigation of Angled Fish Protection Systems—Comparison of Circular Bars and Cables

The requirements for fish protection at hydro power plants have led to a significant decrease of the bar spacing at trash racks as well as the need of an inclined or angled design to improve the guidance effect (fish-friendly trash racks). The flexible fish fence (FFF) is a new developed fish protection and guidance system, created by horizontally arranged steel cables instead of bars. The presented study investigated experimentally the head loss coefficient of an angled horizontal trash rack with circular bars (CBTR) and the FFF with identical cross sections in a flume (scale 1:2). Nine configurations of different bar and cable spacing (blockage ratio) and rack angles were studied for CBTR and FFF considering six different stationary flow conditions. The results demonstrate that head loss coefficient is independent from the studied Bar–Reynolds number range and increases with increasing blockage ratio and angle. At an angle of 30 degrees, a direct comparison between the two different rack options was conducted to investigate the effect of cable vibrations. At the lowest blockage ratio, head loss for both options are in similar very low ranges, while the head loss coefficient of the FFF increases significantly compared to the CBTR with an increase of blockage. Further, the results indicate a moderate overestimation with the predicted head loss by common head loss equations developed for inclined vertical trash racks. Thus, an adaption of the design equation is proposed to improve the estimation of head loss on both rack options.

How the introduction of OSCEs has affected the time students spend studying: results of a nationwide study

BackgroundMedical schools globally now use objective structured clinical examinations (OSCEs) for assessing a student’s clinical performance. In Germany, almost all of the 36 medical schools have incorporated at least one summative OSCE into their clinical curriculum. This nationwide study aimed to examine whether the introduction of OSCEs shifted studying time. The authors explored what resources were important for studying in preparation for OSCEs, how much time students spent studying, and how they performed; each compared to traditionally used multiple choice question (MCQ) tests.MethodsThe authors constructed a questionnaire comprising two identical sections, one for each assessment method. Either section contained a list of 12 study resources requesting preferences on a 5-point scale, and two open-ended questions about average studying time and average grades achieved. During springtime of 2015, medical schools in Germany were asked to administer the web-based questionnaire to their students in years 3–6. Statistical analysis compared the responses on the open-ended questions between the OSCE and MCQs using a paired t-test.ResultsThe sample included 1131 students from 32 German medical schools. Physical examination courses were most important in preparation for OSCEs, followed by class notes/logs and the skills lab. Other activities in clinical settings (e.g. medical clerkships) and collaborative strategies ranked next. Conversely, resources for gathering knowledge (e.g. lectures or textbooks) were of minor importance when studying for OSCEs. Reported studying time was lower for OSCEs compared to MCQ tests. The reported average grade, however, was better on OSCEs.ConclusionsThe study findings suggest that the introduction of OSCEs shifted studying time. When preparing for OSCEs students focus on the acquisition of clinical skills and need less studying time to achieve the expected level of competence/performance, as compared to the MCQ tests.

Surgical anatomy of the nasal and paranasal sinuses in Egyptian native sheep (Ovis aries) using computed tomography and cross sectioning.

The present work aimed to describe the normal computed tomography (CT) and cross-sectional anatomy of the nasal and paranasal sinuses in sheep and to correlate these features with the relevant clinical practices. Twenty apparent healthy heads of Egyptian native breed of sheep (Baladi sheep) of both sexes were used for studying these sinuses. CT images and their closely identical cross sections of the same head were selected and serially labelled in a progression from the rostral nasal region to the caudal aspect of the head using cheek teeth as landmarks. The current investigation reported seven sinuses in sheep, including maxillary, frontal, lacrimal and sphenoidal as paranasal, as well as dorsal and middle conchal and ethmoidal as nasal with unnoticeable palatine and ventral nasal conchal sinuses. The boundaries, extension, structure and communications of these sinuses were fully described. The current study provided anatomical guidelines for surgical interference in the frontal and maxillary sinuses during trephination, dehorning and sinuscopy. Also, an acceptable anatomical explanation was reported in this study for the high incidence of maxillary sinusitis than other sinuses. CT and cross-sectional anatomy could be used as helpful database for diagnosis and clinical interference of the nasal and paranasal sinuses in sheep.

Distribution, nature, and origin of CXCL14-immunoreactive fibers in rat parotid gland

The distribution and nature of CXCL14-immunoreactive nerve fibers in salivary glands, especially the parotid gland was immunohistochemically investigated. Furthermore, the origin of parotid CXCL14-immunoreactive nerve fibers was determined by retrograde tracing experiments. CXCL14-immunoreactive nerve fibers were localized in the parotid, submandibular, and sublingual glands, particularly in the parotid gland. Double staining using identical sections revealed that a subpopulation of cells neuropeptide Y (NPY)-containing fibers was immunopositive for CXCL14 in the parotid gland. In the peripheral regions of acinar cells, CXCL14-immunoreactive fibers tended to coexist with NPY; however, perivascular NPY-immunoreactive fibers tended to be immunonegative for CXCL14. Parotid CXCL14-immunoreactive fibers were immunopositive for tyrosine hydroxylase (TH) but immunonegative for choline acetyltransferase and vasoactive intestinal peptide (VIP). After injection of horseradish peroxidase-labeled wheat germ agglutinin (WGA-HRP) in the parotid gland, retrogradely labeled neurons were seen in the superior cervical ganglion (SCG) and otic ganglion. Some of the WGA-immunoreactive somata in the SCG were immunopositive for CXCL14; however, no doubly-labeled somata were noted in the otic ganglion. These results indicate that CXCL14-immunoreactive nerve fibers originate in the SCG, and are sympathetic in nature. The coexistence of CXCL14 with NPY/TH suggests that CXCL14 may be associated with NPY/TH functions as a neuromodulatory chemokine in the parotid gland. The localization of CXCL14 nerve fibers around the acinar cells of the parotid gland indicates its involvement in acinar cell function, but not vasoconstriction.

Combined Filter for Purifying a Radioactive Steam-Gas Mixture

The design of a new fireproof combined filter for purifying a radioactive steam-gas mixture by removing volatile compounds of radioactive iodine during normal operation of NPP as well as during accidental depressurization of fuel rods is described. The filter consists of identical cylindrical sections, each of which possesses a top lid for anchoring spiral filtering elements with variable surface area and a bottom lid with a grid for anchoring sorbents. The first and closing sections along the course of the purified gas flow are filled with sorbent consisting of the inorganic material SiO2–Cu0 or KSKG brand silica gel or a mixture of the two. A granulated sorbent based on SKT-3I brand activated charcoal or Fizkhimin inorganic granulated sorbent based on silica gel is used as a filler in each of the intermediate sections to catch volatile forms of radioactive iodine. The size of the pores in the spiral filtering elements with variable surface area decreases in a direction from the first to the closing section along the course of the purified gas flow; there are at least three sections equipped with sorbent for purifying gases by removing radioactive iodine-containing impurities.

Scheduling Repetitive Construction Processes Using the Learning-Forgetting Theory

One of the main factors having a decisive impact on the completion date of a construction project and its total cost is the duration of individual processes. Projects such as the construction of multi-storey residential and public buildings, line facilities, highways, networks of external installations or pipelines are conducted with time-location methods of work organization. It is possible to notice the cyclical nature of building processes in projects, whose characteristic parameter is length or height. In such cases, works are entrusted to specialized organizational units (crews, teams) that conduct repeated operations on identical or similar sections, called units. With each repetition of the operations, workers acquire more and more practical experience which has a positive effect on their work efficiency and leads to a reduction in the time and cost of a construction project. The learning theory bring on a mathematical description of the interdependence between the repetitions number of the same task and work efficiency. Taking into account the learning effect allows for a more accurate estimation of the individual construction processes duration, which may provide an advantage at the stage of submitting bids in tenders. The aim of research is to prepare the implementation plan of repetitive construction processes conducted in a multi-storey residential building. The schedule will take into account the impact of the learning and forgetting effect for the duration of construction works and the interruptions in crews work on the example of finishing works. Due to the lack of commercial software for preparing construction schedules taking into account the learning and forgetting impact, a spreadsheet was developed in MS Excel to set the start and end dates and time buffers of construction processes.

Influence of angular damping coupling on the vibrations of a triaxial two-section non-suspension wheeled vehicle

This article is devoted to the study of the influence of angular damping coupling (АDС) on the vibrations of a triaxial two-section non-suspension wheeled vehicle. To assess the effect of the damper in the articulation unit on the vibrations of such a vehicle, three options for combining the parameters of the suspension system and the ADC are considered: wheeled articulated vehicle with suspension and without ADC; wheeled articulated vehicle without suspension and without ADC; wheeled articulated vehicle without suspension and with ADC. Based on the generally accepted assumptions of the linear theory of suspension, a calculation scheme and a mathematical model of the angular oscillations of a triaxial two-section non-suspension wheeled vehicle with ADC in the articulation unit are presented. During finding analytical solution, expressions for the gain of oscillations for the folding angle of identical sections were found and their maximum values in resonance were determined. For the considered options, the ratios of the amplification coefficients of the angular oscillations in resonance and the expressions for the relative damping coefficient of the oscillations along the folding angle of the sections are determined. The calculated amplitude-frequency characteristics (AFC) of the folding angle of the sections for various combinations of ADC parameters in the presence and absence of suspension of the vehicle sections are presented. It is established that the introduction of ADC for a wheeled non-suspension vehicle allows one to reduce the amplitude of angular oscillations in resonance by 10 times. And, when using wheels, the rigidity of which is equal to the stiffness of the suspension, for non-suspension articulated vehicles, an even greater decrease in angular oscillations to a dynamic coefficient of 1,7 is possible. At the same time, the angular damper for the non-suspension vehicle, the inelastic resistance of which is equal to the total power of all 8 shock absorbers of the sprung vehicle, provides smaller angular oscillations in the entire frequency range of the kinematic disturbance on the side of the road. It is advisable to use the proposed articulated layout arrangement of non-suspension vehicle with UDS for developing promising wheeled vehicles, for example, tractors and heavy vehicles with large-diameter wheels.

Ways of reproduction and transfer of the natural gas combustion heat and density units in Ukraine

The article presents the rationale for the need to develop in Ukraine the industry of metrological support for measuring the heat of combustion and density of natural gas. The analysis of available state primary measurement standards of energy units and molar fraction of gas components regarding the possibility of implementing the reproduction of these units has been carried out. The arguments on the need to perform a conformity assessment of these measuring instruments in accordance with the requirements of Technical Regulations have been provided. The example of the implementation of the reproduction of units of heat of combustion and density of natural gas in Germany in the framework of the implementation of the GERG project. The concept of building a reference complex based on a gravimetric setup with the prospect of simultaneously reproducing the units of gas density, mass and volumetric heat of gas combustion direct method with the highest possible accuracy has been proposed, that will insure traceability to units of the New SI system. The use of the method of differential weighing and providing a quasi-stable thermodynamic state for the implementation of the reference densimeter is justified. To ensure the reproduction of the gas volumetric heat combustion unit, a piston-type volumetric gas flow calibrator is used, constructed on the principle of parallel use of three identical piston sections. Such a design will enable to provide a stable value of the volumetric flow of gas entering the calorimeter burning column. The calorimeter should contain elements to control the security parameters the stoichiometric combustion. It is proposed to use a set of standard gas mixtures together with direct-acting comparators to realize the transfer of units to the lower levels of the traceability chain.