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This paper aims to propose and demonstrate a simple fiber optic sensor using a tapered plastic multimode fiber as a probe for measurement of calcium nitrate concentrations in de-ionized water.

The working mechanism is based on the observed increment in the transmission of the sensor that is immersed in calcium nitrate solution of higher concentration. The tapering of the plastic fiber is carried out by etching method using acetone, sand paper and de-ionized water.

Tapered fiber with diameter 0.45 mm gives the highest sensitivity of 0.028 mV/% due to better interaction between the evanescent field and the calcium nitrate solution with a good slope linearity of more than 98 per cent for a 1.07 per cent limit of detection in a straight probe arrangement. The use of calcium and nitrate ions within the sensing medium demonstrates the strong dependency of the sensor output trend on the electrolytic nature of the chemical solutions.

Demonstration of tapered plastic multimode fiber sensor probe for measurement electrolytic chemical solutions.

A simple tapered plastic optical fiber (POF) sensor is proposed and demonstrated for measurement of uric acid concentrations in de-ionized water. The paper aims to discuss these issues.

The sensor operates based on intensity modulation technique as the tapered POF probe which was coated by a single walled carbon nonotubes polyethylene oxide (SWCNT-PEO) composite is immersed into the uric acid solution. The probe was fabricated using an etching method and has a waist diameter of 0.46 mm and tapering length of 10 mm.

As the concentration varies from 0 to 500 ppm, the output voltage of the sensor increases linearly from 6.13 to 7.35 mV with a sensitivity of 0.0023 mV/% and a linearity of more than 97.20 percent. The SWCNT-PEO composite coating increases the sensitivity of the proposed sensor due to the effective cladding refractive index, which increases with the coating and thus allows more light to be transmitted from the tapered fiber.

This is the first demonstration of the tapered POF sensor for measurement of uric acid concentrations in de-ionized water.

The purpose of this study is to investigate the aerodynamic characteristics of a low-to-moderate-aspect-ratio, tapered, untwisted, unswept wing, equipped of sheared wing tips.

In this work, wind tunnel tests were made to study the influence in aerodynamic characteristics over a typical low-to-moderate-aspect-ratio wing of a general aviation aircraft, equipped with sheared – swept and tapered planar – wing tips. An experimental parametric study of different wing tips was tested. Variations in its leading and trailing edge sweep angle as well as variations in wing tip taper ratio were considered. Sheared wing tips modify the flow pattern in the outboard region of the wing producing a vortex flow at the wing tip leading edge, enhancing lift at high angles of attack.

The induced drag is responsible for nearly 50% of aircraft total drag and can be reduced through modifications to the wing tip. Some wing tip models present complex geometries and many of them present benefits in particular flight conditions. Results have demonstrated that sweeping the wing tip leading edge between 60 and 65 degrees offers an increment in wing aerodynamic efficiency, especially at high lift conditions. However, results have demonstrated that moderate wing tip taper ratio (0.50) has better aerodynamic benefits than highly tapered wing tips (from 0.25 to 0.15), even with little less wing tip leading edge sweep angle (from 57 to 62 degrees). The moderate wing tip taper ratio (0.50) offers more wing area and wing span than the wings with highly tapered wing tips, for the same aspect ratio wing.

Although many studies have been reported on the aerodynamics of wing tips, most of them presented complex non-planar geometries and were developed for cruise flight in high subsonic regime (low lift coefficient). In this work, an exploration and parametric study through wind tunnel tests were made, to evaluate the influence in aerodynamic characteristics of a low-to-moderate-aspect-ratio, tapered, untwisted, unswept wing, equipped of sheared wing tips (wing tips highly swept and tapered).

The purpose of this paper is to propose and optimize plastic optical fiber (POF) probe with macro-bending biconical tapered structure for the relative humidity (RH) sensing.

In this study, the principle is the evanescent wave power modulated by the ambient humidity. The probe is fabricated by using fused biconical taper and heat-setting method and then coated with a fluorescent moisture-sensitive film.

The probe’s sensing performance can be optimized by changing the probe’s curvature radius, biconical tapered transition length and taper waist diameter. The result shows that the sensitivity of the probe is up to 1.60 and 3.40 mV/ per cent, respectively, at low humidity (10-45 per cent) and high humidity (45-90 per cent). Also, this probe has good linearity, repeatability, photostability and long-term stability.

The proposed probe can improve the sensitivity and linearity of RH sensing without complex devices, which is necessary for mass production, remote measurement and convenient operation.

POF probe with macro-bending biconical tapered structure is investigated in this paper, which is proved to be effective in improving the sensitivity and linearity.

THE fundamental problem of aerofoil theory is to predict accurately the characteristics of wings of various sections and plan form when the former may be any function of the latter. The vortex theory of aerofoils enables us to predict the chief properties of aerofoils below the stall. We are, however, interested also in the conditions obtaining at and above the stall. In the present state of the art we are obliged to rely on wind tunnel tests. The number and variety of wings that would have to be tested in order to give us at all a comprehensive survey of the possibilities of taper, aerodynamic twist and varying section are so great that wind tunnel tests can so far only be said to have touched the fringe of the problem.

The purpose of this paper is to assess whether the adaptation to fire of current proposals/design methodologies at normal temperature is capable of producing accurate predictions of resistance for the out-of-plane stability of tapered beams.

The adaptation of these methodologies to fire has been done by accounting for the reduction in steel material properties with the temperature. Results were then compared to FEM calculations by performing GMNIA analyses to determine the ultimate strength of the numerical models and to ascertain the validity and accuracy of the adapted methodologies.

Although all methodologies produce safe results at normal temperatures, only the general method is recommended for the safety verification at elevated temperatures, although the data points were overly conservative. This investigation demonstrates the need of proper and accurate design methods for tapered beams at elevated temperatures, which should be the subject of future developments.

The research in this paper is limited to the adaptation of existing room temperature design methods to fire. Therefore, possible assumptions made during the conception of the initial formulae, which may be valid exclusively for 20ºC, may have been disregarded.

For the time being, design methodologies for the safety check of tapered beams for the case of fire are inexistent. This paper investigates the adaptation of existing room temperature design to the fire situation by providing insights on their accuracy level, as well as on how to proceed. Finally, a safe design methodology for tapered beams in case of fire is provided until improved design methods are developed.

This study aims to analyze the roller dynamic characteristics and cage whirling of tapered roller bearing considering roller tilt and skew which provide a theoretical basis for the design and application of tapered roller bearing.

Based on rolling bearing dynamic analysis, the dynamic differential equations of tapered roller bearing are established. Fine integral method and predict correct Adams–Bashforth–Moulton multi-step method are used to solve the dynamic differential equations of tapered roller bearings.

Friction at the flange contact between roller and large flange is the chief factor of roller skew. In comparison to cone speed, axial loads have more visible effect on roller skew, and proper speed or axial load is beneficial to sustain cage motion and decrease cage instability. Under the combined effort of axial load and radial load, the distribution of roller skew is correlated to the roller-flange contact load. In addition, roller skew angle in loaded zone is larger than that in unloaded zone; hence, it is helpful for cage stability if an extent radial load is applied. The pocket clearance of cage has very small influence on roller skew; therefore, a reasonable pocket clearance is suggested to assure minimum instability of cage. Friction coefficient of flange contact has a large effect on roller skew, and cage whirl is found to demonstrate a circular orbit with increasing friction coefficient.

The dynamic differential equations of tapered roller bearing considering roller large end/inner ring back face rib contact under various lubrication states were established. The impact of flange friction working conditions and cage pocket clearance on cage instability and roller skew were focused on. It is the first time that the ratio of the standard deviation of the cage-center translational speed to its mean value is used to access the instability of cage in tapered roller bearing.

The Tapered Roller Bearing had its origin as far back as 1895 when H. H. Timken of America first designed and manufactured the tapered roller bearing for application to the wheel hubs of horse drawn waggons and carriages. That the original design was correct has been substantially proven by the fact that despite continued research we have not been able to depart fundamentally from the basic principles governing the original conception of a tapered roller bearing. In his paper, the late Mr. Snedden (British Timken Ltd.) outlined these basic principles and then went on to discuss the application of tapered roller bearings to rolling mill roll necks, and this is the section of his paper that we reproduce below.

To perform studies and comparisons on the electromagnetic band‐gap (EBG) structures, which are constructed by using a combination of inductive and capacitive elements printed on guided‐wave transmission lines, and by applying a chirping‐and‐tapering technique.

An in‐house solver based on finite‐difference time‐domain (FDTD) method is adopted for analysis. Conventionally, EBG characteristics are formed by a series of perforations, considered as capacitive elements, on the ground plane(s). To enhance the performance, an additional inductive element is implemented, which is realized by narrowing the strip over the respective perforated regions. For further enhancement, a chirping‐and‐tapering technique is applied on the combined EBG structures for comparisons.

Through scattering parameter analysis, it was found that the EBG structures using combined inductive and capacitive elements exhibit a band‐gap behavior superior to the ones built with only inductive or capacitive elements. In another set of comparisons, the modified EBG structures combined with a chirping‐and‐tapering technique resulted in further widening of band‐gap, as well as lower side‐lobes and a smoother transition towards the band‐gap region.

Research was mainly limited to studying solely the EBG structures printed on guided‐wave transmission lines.

The proposed EBG structures may be applied into various areas, such as microelectronics and mobile communications for harmonic suppressions, and into other practical electronic circuit structures.

The ideas on applying combined inductive and capacitive elements on various guided‐wave transmission lines to induce EBG characteristics, together with applications of a chirping‐and‐tapering technique on the combined EBG structures give rise to the research originality.

This paper aims to study the sliding wear and coefficient of friction (COF) using “ball on disc” tribometer. Discs of bearing steel were subjected to different tribological parameters such as heat treatment (through hardening and case hardening), sliding speed, sliding distance and micro-geometry of the functional ball and disc point contact. Results obtained from tribometer were correlated with the preload loss in tapered roller bearing. Preload loss is subjected to wear rate pattern with respect to the internal geometry and micro-geometry of functional surfaces of the tapered roller bearing, caused by internal resistance between roller large ends sliding against cone supporting face. This confirms the optimum geometry and physical/mechanical property of the tapered roller bearing, which makes the use of these bearings under the demanding application in the automotive industry such as differential gears and installation of pinions of differential gears in power transmissions or wheels.

The paper opted for an exploratory study using the design of experiments with full factorial method. The approach was to do ball on disc sliding wear test and correlate that sliding wear with preload loss in tapered roller bearing.

The paper provides the limit of preload loss in tapered roller bearing.

Because of the chosen research approach, the research lacks the effect of environmental conditions such as temperature and relative humidity and lube film thickness effect on wear test. It also lacks the validation part with actual preload loss on tapered roller bearings. Above work is included in future scope of work.

This paper includes the recommendation for surface parameters which can increase the bearing life by reducing the preload loss in tapered roller bearing.

This paper includes the recommendation for surface parameters for bearing manufacturing industries.

This paper provides the relation between sliding wear and preload loss in tapered roller bearing.