Aluminum-based composites are in high demand in industrial fields due to their light weight, high electrical conductivity, and corrosion resistance. Due to its unique advantages for composite fabrication, powder metallurgy is a crucial player in meeting this demand. However, the size and weight fraction of the reinforcement significantly influence the components' quality and performance. Understanding the correlation of these variables is crucial for building high-quality components. This study, therefore, investigated the correlations among various parameters—namely, milling time, reinforcement ratio, and size—that affect the composite’s physical and mechanical properties. An artificial neural network model was developed and showed the ability to correlate the processing parameters with the density, hardness, and tensile strength of Al2024-B4C composites. The predicted index of relative importance suggests that the milling time has the most substantial effect on fabricated components. This practical insight can be directly applied in the fabrication of high-quality Al2024-B4C composites.
With the booming popularity of social media such as facebook and Wechat, more and more people and firms commence to utilize it to promote products and services. The convenience of sharing personal experience online, however, also leads to increasing number of consumer to complain through online reiews. For example, negative online review has increased 800% over the years between 2014 and 2015 (Causon 2015) and has negative impact on many viewers’ buying decisions (Chevalier, & Mayzlin, 2006). Therefore, it is important to investigate what factors would reduce the negative impact of other customers’ online complaints on consumer purchase intention. Developing friendships with customers through social media is a common strategy for service provider to retain customers. Prior literature suggests that consumers in general are more tolerant of a service failure when the service provider is having a friendship with the customer than when the provider is having a business relationship (Wan, Hui, and Wyer 2011). Therefore, we suggest that friendship could also attenuate the negative impact of an online complaint from other customer on consumer purchase intention. Furthermore, we predict that this could happen only in the self-consumption situation. In the consumption situation of buying gifts for others, friendship would no longer attenuate the impact of a negative online review on consumer purchase intention. It is because gift giving involves sybolic value of face enhancement in developing social relationships with the gift giving target. Consumers would be less likely to take risks of buying substandard products as gifts. Implications and future research directions will be discussed.
Although the majority of prior literature has suggested the key reasons for consumer complaining in service failures are to vent negative emotions (e.g. anger, dissatisfaction) and to seek redress (Blodgett, Hill, & Tax 1997; Nyer 1997), some research has also pointed out that customers will give constructive suggestions to firms through complaining (Groth, 2005; Liu & Mattila, 2015). In this regard, consumer complaining can be classified into two types, namely, positive complaint (i.e., with constructive suggestion) and negative complaint (i.e., without constructive suggestion). Understanding what situations would dissatisfied consumers choose to give constructive suggestions in service failures would be of utmost important to firms. We suggest that a firm’s brand image may affect consumers’ intention to choose what types of complaint in service failures. In general, consumers may perceive a brand as having a competence image (e.g., professional and efficient) or having a warmth image (e.g., friendly and approachable) (Kervyn, Fiske and Malone, 2012). Comparatively speaking, a warmth image is associated with friendship and caring, whereas a competence image is associated with expertise. Therefore, it is possible that consumers would have a higher empathy and intention to help a firm with a warmth (vs. competent) image, and be more likely to choose positive complaint when a failure happens to this firm. An experimental study confirmed this prediction. In addition, we found that although a firm’s competence (vs. warmth) image does not affect the likelihood to give constructive suggestions in service failures, it leads to a higher level of return intention. Implications and future research directions will be discussed.
This research addresses an important, yet under-researched, issue concerning the management of loyalty programs (LPs) in the era of globalization: how to effectively motivate LP members from different cultures to continue the reward pursuit process. Drawing on cross-cultural research and regulatory fit theory, we identify feedback framing as a low-cost, easy-to-implement strategy for building program loyalty across cultures. Two cross-cultural studies confirm all the hypotheses about the effects of feedback framing. Overall, this research advances theoretical understanding of reward pursuit behavior across cultures and offers practical advice for managing LPs in different cultural contexts.
Polarbear is a ground-based experiment located in the Atacama desert of northern Chile. The experiment is designed to measure the Cosmic Microwave Background B-mode polarization at several arcminute resolution. The CMB B-mode polarization on degree angular scales is a unique signature of primordial gravitational waves from cosmic in ation and B-mode signal on sub-degree scales is induced by the gravitational lensing from large-scale structure. Science observations began in early 2012 with an array of 1,274 polarization sensitive antenna-couple Transition Edge Sensor (TES) bolometers at 150 GHz. We published the first CMB-only measurement of the B-mode polarization on sub-degree scales induced by gravitational lensing in December 2013 followed by the first measurement of the B-mode power spectrum on those scales in March 2014. In this proceedings, we review the physics of CMB B-modes and then describe the Polarbear experiment, observations, and recent results.
We first deduce a uniform formula forthe Fermi energy of degenerate and relativistic electrons in the weak-magnetic field approximation. Then we obtain an expression of the special solution for the electron Fermi energy through this formula, and express the electron Fermi energy as a function of electron fraction and matter density. Our method is universally suitable for relativistic electron- matter regions in neutron stars in the weak-magnetic field approximation.
Due to the lack of an accretion disk in a polar (magnetic cataclysmic variable, MCV), the material transferred from the secondary is directly accreted onto the white dwarf, forming an accretion stream and a hot spot on the white-dwarf component. During the eclipses, different light components can be isolated. Therefore, the monitoring of eclipsing polars could provide valuable information on several modern astrophysical problems, e.g., CVs as planetary hosting stars, mass transfer and mass accretion in CVs, and the magnetic activity of the most rapidly rotating cool dwarfs. In the past five years, we have monitored about 10 eclipsing polars (e.g., DP Leo and HU Aqr) using several 2-m class telescopes and about 100 eclipse profiles were obtained. In this paper, we will introduce the progress of our research group at YNOs. The first direct evidence of variable mass transfer in a CV is obtained and we show that it is the dark-spot activity that causes the mass transfer in CVs. Magnetic activity cycles of the cool secondary were detected and we show that the variable mass transfer is not caused by magnetic activity cycles. These results will shed light on the structure and evolution of close binary stars (e.g., CVs and Algols).
Two sintering methods of a pressureless sintering and a spark-plasma sintering are tested to densify the Fe-TiC composite powders which are fabricated by high-energy ball-milling. A powder mixture of Fe and TiC is prepared in a planetary ball mill at a rotation speed of 500 rpm for 1h. Pressureless sintering is performed at 1100, 1200 and 1300oC for 1-3 hours in a tube furnace under flowing argon gas atmosphere. Spark-plasma sintering is carried out under the following condition: sintering temperature of 1050oC, soaking time of 10 min, sintering pressure of 50 MPa, heating rate of 50oC, and in a vacuum of 0.1 Pa. The curves of shrinkage and its derivative (shrinkage rate) are obtained from the data stored automatically during sintering process. The densification behaviors are investigated from the observation of fracture surface and cross-section of the sintered compacts. The pressureless-sintered powder compacts show incomplete densification with a relative denstiy of 86.1% after sintering at 1300oC for 3h. Spark-plasma sintering at 1050oC for 10 min exhibits nearly complete densification of 98.6% relative density under the sintering pressure of 50 MPa.
Fe-TiC composite powders are fabricated by planetary ball mill processing. Two kinds of powder mixtures are prepared from the starting materials of (a) (Fe, TiC) powders and (b) (Fe, TiH2, Carbon) powders. Milling speed (300, 500 and 700 rpm) and time (1, 2, and 3 h) are varied. For (Fe, TiH2, Carbon) powders, an in situ reaction synthesis of TiC after the planetary ball mill processing is added to obtain a homogeneous distribution of ultrafine TiC particulates in Fe matrix. Powder characteristics such as particle size, size distribution, shape, and mixing homogeneity are investigated. In case of (Fe, TiC) powder many coarse TiC particulates with size of several μm are unevenly distributed in Fe-matrix. The composite powder prepared from (Fe, TiH2, C) powder mixture showed a homogeneous dispersion of ulatrafine TiC particulates.
We study the physical and chemical properties of the molecular clump hosting a young stellar cluster, IRAS 20160+3636, which is believed to have formed via the “collect and collapse” process. Physical parameters of the UC Hii region associated with the embedded cluster are measured from the radio continuum observations. This source is found to be a typical Galactic UC Hii region, with a B0.5 type exciting star, if it is ionized by a single star. We derive a CN/HCN abundance ratio larger than 1 over this region, which may suggest that this clump is being affected by the UV radiation from the Hii region.
Fe-TiC composite was fabricated from Fe and TiC powders by high-energy milling and subsequent spark- plasma sintering. The microstructure, particle size and phase of Fe-TiC composite powders were investigated by field emission scanning electron microscopy and X-ray diffraction to evaluate the effect of milling conditions on the size and distribution of TiC particles in Fe matrix. TiC particle size decreased with milling time. The average TiC particle size of 38 nm was obtained after 60 minutes of milling at 1000 rpm. Prepared Fe-TiC powder mixture was densified by spark- plasma sintering. Sintered Fe-TiC compacts showed a relative density of 91.7~96.2%. The average TiC particle size of 150 nm was observed from the FE-SEM image. The microstructure, densification behavior, Vickers hardness, and frac- ture toughness of Fe-TiC sintered compact were investigated.
TiB2-reinforced iron matrix composite (Fe-TiB2) powder was in-situ fabricated from titanium hydride (TiH2) and iron boride (FeB) powders by the mechanical activation and a subsequent reaction. Phase formation of the composite powder was identified by X-ray diffraction (XRD). The morphology and phase composition were observed and measured by field emission-scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively. The results showed that TiB2 particles formed in nanoscale were uniformly distributed in Fe matrix. Fe2B phase existed due to an incomplete reaction of Ti and FeB. Effect of milling process and synthesis temperature on the formation of composite were discussed.