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The purpose of this paper is to investigate propagation characteristics of seismic waves at the welded interface of an elastic solid and unsaturated poro-thermoelastic solid.

A theoretical formulation of partially saturated poro-thermoelastic solid is used in this study established by Zhou et al. (2019). The incidence of two primary waves (P and SV) is taken. The incident wave from the elastic solid induces two reflected waves and five refracted waves. Due to viscous pore fluids, partially saturated poro-thermoelastic solid behave dissipative, whereas elastic solid behaves non-dissipative. As a result, both reflected and incident waves are homogeneous. However, all the refracted waves are inhomogeneous. A non-singular system of linear equations is formed by the coefficients of reflection and refraction for a specified incident wave. The energy shares of various reflected and refracted waves are determined by using these reflection and refraction factors. Finally, a sensitivity analysis is performed, and the effect of critical variables on energy partitioning at the interface is observed. The numerical example shows that throughout the process of reflection/refraction, the energy of incidence is conserved at all angles of incidences.

This study demonstrated two refracted (homogeneous) and five refracted (inhomogeneous) waves due to the incident wave from elastic solid. The reflection and refraction coefficients and partitioning of incident energy are acquired as a part of diverse physical parameters of the partially saturated poro-thermoelastic media. The interference energies between unlike pairs of refracted waves have been discovered due to the dissipative behavior of unsaturated poro-thermoelastic solid.

The sensitivity of different energy shares to various aspects of the considered model is graphically analyzed for a specific numerical model. The energy balance is maintained by combining interaction energy and bulk wave energy shares.

The purpose of this research is to study the reflection and refraction of elastic waves at the interface of an elastic half‐space and initially stressed thermoelastic with voids half‐space.

A two‐dimensional model was considered of an isotropic elastic half‐space (medium I) lying over a homogeneous isotropic generalized initially stressed thermoelastic with voids half‐space(medium II). There exist two waves, P‐wave and SV‐wave in isotropic elastic half‐space and three quasi‐longitudinal waves namely, quasi‐longitudinal wave (QP‐mode), quasi‐longitudinal thermal wave (QPT‐mode), quasi‐longitudinal volume fractional wave (QPV‐mode) and one quasi‐transverse wave (QSV‐mode) exists in initially stressed thermoelastic with voids half‐space.

The energy ratios of these waves are computed along various directions of incident wave, and it is found that the sum of all energy ratios is exactly unity at each value of incident angle. The amplitude ratios of various waves were obtained numerically.

Reflection and refraction of an elastic medium is of great practical importance. Since valuable organic and inorganic deposits beneath the earth surface are difficult to detect by drilling randomly, wave propagation is the simplest and most economic technique to these and does not require any drilling through the earth. Almost all the oil companies rely on seismic interpretation for selecting the sites for exploratory oil wells because seismic wave methods have higher accuracy, higher resolution and more economical, as compared to drilling which is expansive and time consuming.

The effects which are produced by pearlescent pigments are intimately connected to optics and the interaction of light with matter. Pearlescent pigments are optical filters which reflect and transmit light which falls upon them. In order to understand pearlescent pigments, therefore it is first necessary to understand some of the basic laws of optics. I would like to review some of these laws to talk about light and its interaction with matter, how it can be separated into its components, the laws of reflection and refraction and how all of these laws apply to pearlescent pigments.

Both the current long term telecommunication trends toward optical networking and the recent growth in information bandwidth have pushed the necessity for improved optical communications. Our fabrication approach, which leverages our expertise in solid freeform fabrication in conjunction with sol‐gel technology, has advantages over these other methods because of the inherent benefits of using a direct‐write philosophy, such as design flexibility and minimal post‐processing. However, fabrication of such novel optical components requires extensive knowledge of their light guidance capabilities. This paper shows the technical issues involved in both modeling and characterizing small optical components fabricated by locally densifying sol‐gels in a modified direct‐write process.

Effective refractive error (RE) coverage in a resource-constrained country such as Kenya could possibly be achievable if the current dominant commercial entrepreneurship is supplemented with alternative avenues such as social entrepreneurship. This study aims to explore the perceived impact of social enterprises (SEs) in scaling effective RE coverage in Kenya.

This was an exploratory study with data collected from representatives of SEs (n = 29), trainees of SEs (n = 112) and beneficiaries of eye care services provided by SEs (n = 674). Participants were recruited purposively with data collected through telephonic calls. Thematic analysis was carried out by categorizing the codes into categories and themes based on the semantic meaning of the codes.

The perceived impact of SEs from the representative perspective included entrepreneurship and livelihood (n = 3; 10.3%), skills development (n = 20; 69%), technology development (n = 7; 24.1%), access to specialized services (n = 7; 24.1%) and affordability, accessibility and availability of RE services (n = 27; 93.1%). From the perspective of trainees, the themes included economic empowerment (n = 99; 88.4%), improved quality of life (n = 84; 75.0%), sensitizing locals to RE during screening events (n = 112; 100.0%) and enhancing accessibility, availability and affordability (n = 107; 95.5%).

The perceived impact of SEs highlighted in this paper showcases that they are useful for integration into the eye health ecosystem in a resource-constrained country such as Kenya. Integration of SEs into the eye health ecosystem could potentially address the human resource challenge, scale RE service delivery, enhance awareness creation and address the cost barriers to current RE service delivery coverage.

The bulk of jet engine noise developed at high powers arises from the turbulent mixing of the jet efflux in the surrounding air, as judged from model experiments, and has a continuous spectrum with a single flat maximum. The high frequency sound arises from fairly close to the orifice, and reaches its maximum intensity at fairly large acute angles to the jet direction. Lower frequency noise arises from lower down stream and its maxima make smaller acute angles with the jet axis. The possible origins are briefly discussed in view of Lighthill's theory and refraction effects. The most intensesound has a wave‐length of the order of three or four exit diameters, and originates between five and ten diameters from the orifice. A semi‐empirical rule of noise energy depending on the jet velocity to the eighth power and the jet diameter squared gives a rough estimate of the noise level for both cold and heated jets. Further noise from heated or supersonic jets may occur through eddies travelling at supersonic speed and so producing small Shockwaves. Model experiments have shown that interaction between shock‐wave configurations in choked jets and passing eddy trains generates sound and this initiates further eddies at the orifice. The directional properties of this sound are quite distinctive, the maximum being in the upstream direction. Methods of reducing jet noise are briefly discussed.

The purpose of this paper is to refract March’s views on leadership to re-frame them within an authentic model that understands optimistic failure and mindful resilience as likely byproducts of enabling ambiguous innovation. An analysis of March’s theories of slack, and the concepts of exploration and exploitation, as well as that of foolishness, are used to support the adoption of authentic and ethical leadership as an intelligent practice and, more concretely, to portray the leader as a resilient “juggling fool.”

This paper makes use of primary data by focusing on March’s published works, as well as on interviews and other materials written about him, or those discussing his contributions. A post-hoc practice of “appreciation” facilitated a fresh refraction of the “evidence” to identify or recognize new perspectives and/or challenges to March’s conceptualization of leadership, while relying on literature and metaphor to engage in “polymorphic research.”

This paper presents March as a complex thinker, whose thoughts on leadership have received, perhaps, less attention for being thought to be more refractive and less empirical. Nonetheless, his reflections on leadership re-discover him as a solid leadership philosopher. His use of literature, his theories of slack and the concepts of exploration and exploitation, as well as that of foolishness, may help leadership scholars to understand the essence of authentic and ethical leadership as an intelligent practice.

This paper proposes to extrapolate March’s vast insights about organizational theory to further develop the framework of authentic leadership. This re-framing of the leader as a “juggling fool” constitutes an empowered view of leadership that comes closer to balancing the complementary purposes of leadership and management; an effort that rests at the core of the future of leadership.

Despite the ostensible popularity of leadership over management as a desired organizational outcome, March’s phenomenal insights remind current and developing leaders of just how much the two fields must overlap in constant tension. It is, perhaps, the conceptualization of a leader as an authentic and resilient “juggling fool” what adds depth of meaning to March’s contributions to the field of leadership beyond that of management.

This study aims to develop an assessment strategy for fire damaged infrastructures based on the implementation of quick diagnostic techniques and consistent interpretation procedures, so to determine the residual safety margin and any need for repair works.

In this perspective, several tailored non-destructive test (NDT) methods have been developed in the past two decades, providing immediate results, with no need for time-consuming laboratory analyses. Moreover, matching their indications with the calculated effects of a tentative fire scenario allows harmonizing distinct pieces of evidence in the coherent physical framework of fire dynamics and heat transfer.

This approach was followed in the investigations on a concrete overpass in Verona (Italy) after a coach violently impacted one supporting pillar and caught fire in 2017. Technical specifications of the vehicle made it possible to bound the acceptable ranges for fire load and maximum rate of heat release, while surveillance video footage indicated the duration of the burning stage. Some established NDT methods (evaluation of discolouration, de-hydroxylation and rebar hardness) were implemented, together with advanced ultrasonic tests based on pulse refraction and pulse-echo tomography.

The results clearly showed the extension of the most damaged area at the intrados of the box girders and validated the maximum heating depth, as predicted by numerical analysis of the heat transient ensuing from the localized fire model.

This study aims to propose and study a refractive index sensor based on measuring variations of the internal diffuse reflectance from a glass interface in a functional design. The device is uncomplicated to assemble with simple optical elements and it can be built as a robust and stable sensor.

This study presents a simplified theoretical model of the signal obtained with the proposed device and perform a detailed analysis of its potential resolution and merits.

The authors report proof-of-principle experiments with a home-made device to evaluate its performance as a refractometer and index of refraction sensor.

The main novelty of the device is the use of a diffusing surface to couple light into a glass plate with a wide range of angles of refraction, including angles larger than the critical angle with the external medium, and using the same diffusing surface to couple reflected light out of the glass plate, including light that suffered total internal reflection.

Troposphere delay is one of the important error sources in global positioning system (GPS) positioning. The purpose of this paper is to analyze the accuracy and adaptability of GPS troposphere error correction models, and to provide theoretic foundation for model selection in GPS accurate positioning.

The principle of troposphere delay error effecting on GPS signals is theoretically analyzed. The model peculiarity and modeling method of the four common troposphere delay correction models: Hopfield, Saastamoinen, Black, and Egnos models are discussed detailedly. With the measurement data from Crustal Dynamics Data Information System of the technical support institution for GPS, the accuracy and applicability of the four models are quantificationally studied.

For a low elevation, Hopfield, Saastamoinen, and Black models show great agreement with each other, and have quite high precision. In the zenith direction, the maximal troposphere delay error of three models are all less than 1 dm, but Black and Hopfield models have higher precision than Saastamoinen model. Black model can be regarded as the improved form of Hopfield model: for a high elevation, precision of two models are close, while for a low elevation, Black model shows to be more effective than Hopfield model. The precision of Egnos model is quite lower than that of Black, Hopfield, and Saastamoinen models. However, Egnos model can be a better choice when it is difficult to obtain real‐time meteorological data in certain application environment.

This paper makes thorough research on GPS troposphere delay error correction models. The conclusions are presented for selecting troposphere delay models, which are useful for practical engineering application.