Common Cladding Research Articles

Research status of laser cladding material system on titanium alloy

Abstract Laser cladding technology is an advanced surface modification technology. By selecting different parameters and coating materials, the surface hardness and wear resistance of titanium alloys can be effectively improved. The cladding material is a key factor affecting the quality and performance of the cladding layer. Common cladding materials mainly include self-fluxing alloy powder, ceramic powder and rare earth element powder. This paper reviews the current research status of laser cladding material system on titanium alloy, and explains the problems that still need to be solved and puts forward the outlook.

Durability Assessment of ETICS: Comparative Evaluation of Different Insulating Materials

The External Thermal Insulation Composite System (ETICS) is a common cladding technology that is widely used thanks to its well-known advantages. Despite previous studies dealing with ETICS durability in real-building case studies or involving accelerated ageing tests in climatic chambers, little progress has been made in the knowledge of the long-term durability of the system. In order to realize optimized maintenance plans for this component, the durability of the whole system, and of the most-used insulating materials for the ETICS (i.e., cork, polyurethane, rock wool, glass wool, grey EPS, and fiberfill wood), has been investigated. Based on previous experiments on ageing cycles, different climatic chambers were used to accelerate performance decay by simulating natural outdoor exposure in order to assess different physical and thermal characteristics (thermal transmittance, decrement factor, time shift, water absorption, thermal resistance, and conductivity). Recorded trends show that materials with lower thermal conductivity exhibit lower performance decay, and vice versa. The durability of the ETICS with different insulating materials (as the only variable in the different samples) was evaluated in order to quantify service life and then correctly plan maintenance interventions. Life-cycle assessment must take into account service life and durability for each material of the system. A higher durability of insulating materials allows for the execution of less maintenance interventions, with the loss of less performance over time. This study shows the physical and thermal behavior of the ETICS during its service life, comparing the differences induced by the most-used insulating materials. As a result of accelerated ageing cycles, the analyzed ETICS reveals a low grade of decay and measured performances show little degradation; for thermal conductivity, differences between the measured and the declared conductivities by technical datasheet were observed.

Measuring the effective thermal resistance of ventilated air-spaces behind common wall assemblies: theoretical uncertainty analysis and recommendations for the hot box method modifications (ASHRAE 1759-RP)

A well-designed ventilated wall that incorporates air-space behind cladding can reduce energy use for conditioning buildings by adding a thermally resistive layer. The scarcity of thermal performance data and standardized test methods is a particular barrier for practitioners to implement ventilated air gaps behind the facades. The current standardized test method to evaluate the thermal performance of a wall structure, such as ASTM 1363-19, does not consider the effect of the ventilated air-space behind external claddings. Therefore, testing and design recommendations are required to account for the impact of ventilation airflow on the thermal resistance of vertical air-spaces behind common cladding materials. In this study, the theoretical uncertainty analysis of the effective thermal resistance of the ventilated cavity is performed for a steady-state condition. The results revealed that temperature sensors with an absolute uncertainty of ±0.18 (±0.1 °C) and heat flux sensors with a relative uncertainty of 3% or lower are required to capture a wide range of the effective thermal resistance of the ventilated air gap. Thereafter, based on the uncertainty of temperature and heat flux measurements, the modifications of the ASTM C1363-19 test method to account for the airflow effects on the thermal performance of the wall assembly are proposed. A detailed description of the experimental setup is provided, and protocols for collecting, analyzing, and evaluating data are suggested. An example demonstrating how the proposed method can be practically used to measure the thermal resistance of a ventilated air-space is also presented.

UV-A light induces a robust and dwarfed phenotype in cucumber plants (Cucumis sativus L.) without affecting fruit yield

Solar ultraviolet (UV) light influences plant growth and metabolism. Whereas high doses of UV can be deleterious for plants, natural UV doses are important for morphogenesis in many plants species, including those used in horticulture. Greenhouses are widely used for horticultural production and common cladding materials strongly absorb UV. Thus, low amounts of UV may be limiting the optimal development in some plant species. Light supplementation using UV tubes can overcome UV deficiency. Here we study cucumber seedling production in the absence or presence of different UV wavelengths. UV-A- (315−400 nm) and UV-B- (280−315 nm) enriched light was used for exposure and parameters such as the maximum quantum yield of photosystem II, stem development (internode length and diameter, stem dry weight, stem weight per unit of stem length, and stem bending), root biomass, leaf biomass and specific leaf mass were measured. We found that UV-A supplementation resulted in shorter more compact and sturdy plants, properties that are positive from a horticultural perspective. In contrast, UV-B-enriched light led to even smaller plants that lacked the sturdy stem. There were no signs of decreased Fv/Fm under any of the treatments, nor statistically significant differences in fruit yield between the control plants and the UV-treated plants when grown to harvest. In particular, the differences in fruit yield between the controls and the UV-A-treated plants were negligible in all cases. Thus, supplementary UV-A light can be an interesting alternative to chemical growth regulators for production of sturdy horticultural plants.

Direct Light‐Writing of Nanoparticle‐Based Metallo‐Dielectric Optical Waveguide Arrays Over Silicon Solar Cells for Wide‐Angle Light Collecting Modules

AbstractHere presented are the properties and performance of a new metallo‐dielectric waveguide array structure as the encapsulation material for silicon solar cells. The arrays are produced through light‐induced self‐writing combined with in situ photochemical synthesis of silver nanoparticles. Each waveguide comprises a cylindrical core consisting of a high refractive index polymer and silver nanoparticles homogenously dispersed in its medium, all of which are surrounded by a low refractive index common cladding. The waveguide array‐based films are processed directly over a silicon solar cell. Arrays with systematically varied concentration of AgSbF6 as the salt precursor are explored. The structures are tested for their wide‐angle light capture capabilities, specifically toward enhanced conversion efficiency and current production of encapsulated solar cells. Observed are increases in the external quantum efficiency, especially at wide incident angles up to 70°, and nominal increases in the short circuit current density by 1 mA cm−2 (relative to an array without nanoparticles). Enhanced light collection is explained in terms of the beneficial effect of scattering by the nanoparticles along the waveguide cores. This is a promising approach toward solar cell encapsulants that aid to increase solar cell output over both the course of the day and year.

State-of-the-art multicore fiber amplifiers for space division multiplexing

Space division multiplexing (SDM) has generated much interest lately as a potential means for enhancing the capacity of optical transmission systems. During the past several years, we have observed tremendous research efforts in the development of SDM amplifiers with an aim to increase core and mode counts and to improve amplification properties and pump conversion efficiencies. We report on the recent development of multicore fiber amplifiers suitable for amplifying space division multiplexed signals. Multicore fiber amplifiers with different number of cores, and pumping schemes have been developed to pump the cores individually or through a common cladding. We will report on the structures of SDM amplifiers, their optical properties, and discuss prospects for further development.

Renovation of apartment blocks with BIPV: Energy and economic evaluation in temperate climate

This paper investigates the energy and economic profitability of renovating residential buildings in temperate climate through the integration of PV panels on façades. The investigation regards a real multi-storey apartment block, representative of a significant amount of edifices built in Italy in 1950–1990, which often need refurbishment because of obsolescence. This building type is generally well suited to receive a new double-skin façade, supporting both PV and other common cladding materials, while also representing a good compromise in terms of aesthetic quality, cost, weight, durability and ease of maintenance.In order to make general conclusions, a parametric analysis is performed, by virtually changing the orientation, the number of floors and the climatic conditions, and by considering different PV technologies. The results show that for an 8-storey building with the main axis along E-W, the initial investment can be repaid within around nine years, if considering the current fiscal incentives and a 50% self-consumption rate for the electricity produced by the PV modules. The presence of fiscal incentives is essential to make the investment attractive.Better PV efficiencies, lower prices and higher self-consumption rates can enhance the economic profitability, which may generate a significant impact on the retrofit of European multi-storey residential stock. These results can be effectively extended to the PV integration on the façades of new apartment blocks too.

English

Cladding is a surface modification process in which a specially designed alloy is surface welded in order to enhance corrosion resistant properties. Common cladding techniques include Gas Tungsten Arc Welding (GTAW), submerged arc welding (SAW) and gas metal arc welding (GMAW). Because of high reliability, easiness in operation, high penetration good surface finish and high productivity gas metal arc welding became a natural choice for fabrication industries. This paper presents central composite rotatable design with full replication techniques to predict four critical dimensions of bead geometry. The second order regression method was developed to study the correlations. The developed models have been checked for adequacy and significance. The main and interaction effects of process variables and bead geometry were presented in graphical form. Using fmincon function the process parameters were optimized. Key words: Gas metal arc welding (GMAW), weld bead geometry, mathematical model.

Coupling between optical fibers with left-handed materials

The coupling between optical fibers with left-handed materials is analyzed in this paper. First, we obtain new coupled-wave equations and define new relevant coupling coefficients by using Maxwell's equations. Second, the coupling between two identical fibers with the same left-handed material as the core and the same right-handed material as the common cladding is discussed. The coupling coefficient for TE01 mode is calculated. The coupling coefficient versus distance of two fibers with different normalized frequencies is plotted. Through comparing these curves, some new coupling characteristics between fibers including left-handed materials are obtained.

Weak guidance analysis of the modal characteristics and waveguide dispersion of a new lightguide with a lemniscate of Bernoulli‐type core cross section

AbstractThe purpose of this paper is to introduce a simple analytical technique based on scalar‐wave approximation to study the modal characteristics of a new lightguide having a lemniscate of Bernoulli‐type core cross section. This type of structure may be conceived as a practical situation wherein two cores are embedded in a common cladding. Using lemniscate cylindrical coordinates (ξ, η, z) and the weak guidance boundary conditions, the eigenvalue equation is derived. From this equation, the characteristic curves have been obtained and plotted for some low‐order modes (ν=0). Furthermore, denoting the normalized frequency parameter as ν and the normalized propagation constant as b′, the variation (d(Vb′)/dV) is also obtained and analyzed. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 211–216, 2002.

A high-brightness laser beam from a phase-locked multicore Yb-doped fiber laser array

We observed a high-brightness laser beam emitted from a closely packed array of seven Yb-doped single-mode fiber lasers embedded in a common cladding. The measured slope efficiency, greater than 65%, was achieved by clad-pumping from one end of the fiber. A theoretical model is established to provide a physical interpretation of the measured far field radiation patterns.

Skew characteristics of image fiber for high-speed 2-D parallel optical data link

Skew of an image fiber, which has more than ten thousands of cores in a common cladding, was measured by a novel measurement method for the first time. This method can measure the time-of-flight difference between individual cores over the whole area of an image circle. The measurement result reveals that a test 100-m-long image fiber has skew of 5 ps/m, and the time-of-flight distributes randomly in the whole area of the image circle due to nonuniformity of the core dimension. It is also experimentally shown that the skew of an image fiber increases by bending. The theoretical analysis reveals that the bending-induced skew depends neither on the radius of curvature nor the shape of the curve but it depends only on the number of turns it is wound. The numerical calculation of skew by using typical parameters of image fibers shows that the winding have to be restricted to less than five turns to achieve a transmission speed of over 1 Gb/s/ch. Finally, we propose a twisted image fiber and an 8-shaped bobbin to suppress the skew due to bending.

Modal cutoff behavior of an optical waveguide with a multiloop core cross section embedded in a common cladding

In this paper, a multiloop curve with a rather simple mathematical description in polar coordinates is chosen to describe the core cross-section boundary of a waveguide. This waveguide is used as a model representing a waveguide in which several cores are embedded in a common cladding. The cutoff equation for the lowest order modes is derived using the scalar wave approximation. Numerical computations are made to determine how the cutoff condition is modified as one increases the number of cores (loops) from three to ten. It is found that a waveguide with a crossection having fewer loops sustains more modes than that with a greater number of loops. © 1998 John Wiley & Sons, Inc. Microwave Opt Technol Lett 19: 196–200, 1998.

Modal cutoff behavior of an optical waveguide with a multiloop core cross section embedded in a common cladding

Modal cutoff behavior of an optical waveguide with a multiloop core cross section embedded in a common cladding

Modal cutoff properties of a fiber with a trefoil cross section under the weak guidance approximation

In this paper, we present a theoretical analysis of the propagation of electromagnetic waves through a fiber with a trefoil cross section. This may be regarded as a preliminary study of a waveguide in which three cores are embedded in a common cladding. By choosing an appropriate coordinate system, the scalar wave equation is solved, and thereby the characteristic equation for the guided modes under the weak guidance approximation is derived. To understand the basic modal properties in a simple manner, the cutoff equation is derived, and the modal cutoff properties of some modes are determined numerically. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 16: 85–89, 1997.

Cross-talk fiber-optic temperature sensor

The temperature sensitivity of cross talk between closely spaced cores in a common cladding is calculated and compared with measurements. A periodic variation in core contrast is observed when one core is illuminated and the temperature is changed. The variation in light distribution, which is ascribable to a change in coupling between the cores, agrees with theoretical predictions. It is shown that cross talk can be made to be a sensitive, predictable function of temperature or by proper selection of materials, wavelength, and fiber geometry essentially temperature independent.