Two MILP models for the N × M SDST flowshop sequencing problem

This paper presents the derivation and evaluation of two new MILP models for the SDST flowshop sequencing problem. The first model, TS1, was derived directly from the assignment-problem-based MILP model for the regular flowshop that Stafford modified from the original Wagner three-machine all-integer model. The second model, TS2, combined the properties of model TS1 with the looser constraints approach of Srikar and Ghosh, as modified by Stafford and Tseng (model SG*). Three experiments were used to compare both new models to the SG* model. Both new models were found to use significantly less computation time than the SG* model, especially for problem sizes of 6 or more jobs and 5 or more machines. The TS1 model used significantly less computation time than the TS2 model, making it the current best MILP model in the SDST flowshop literature.     

Group-Based Authentication and Key Agreement

This paper presents an authentication and key agreement protocol to streamline communication activities for a group of mobile stations (MSs) roaming from the same home network (HN) to a serving network (SN). In such a roaming scenario, conventional schemes require the SN to interact with the HN for authenticating respective MSs, at the cost of repeated message exchanges and communication delay. Instead, in our design, when the first MS of a group visits, the SN performs full authentication with the concerned HN and thereby obtains authentication information for the MS and other members. Thus when any other MS of the same group visits, the SN can authenticate locally without subsequent involvement of the HN, so as to simplify protocol operations. We will show that our scheme does not trade performance for security and robustness to the extent that security requirements are unduly weakened. Both qualitative and quantitative discussions indicate that our proposed scheme lends itself to pragmatic settings.     

Cathodoluminescence and Field-Emission Properties of β-Ga2O3 Nanobelts

β-Ga₂O₃ nanobelts were synthesized using a vapor transport process in a controlled ambient. Structural characterization revealed that the as-synthesized samples consisted of monoclinic β-Ga₂O₃ nanobelts, and the presence of gallium-associated defects was verified using cathodoluminescence (CL). The formation of gallium-associated defects was explained by the insufficiency of the supply of cations, generating gallium vacancies on the (010) facet during growth. Furthermore, field-emission measurements indicated that β-Ga₂O₃ nanobelts exhibited defect-related electron emission. The turn-on fields of β-Ga₂O₃ nanobelts increased significantly with the degree of structural defects. For a sample prepared under 15% ambient oxygen, Fowler–Nordheim (F–N) analysis revealed two distinct field-enhancement factors of 1194 and 276, respectively. A correlation between field emission and structural defects was proposed. The experimental results demonstrate the presence of gallium-associated defects, which behave as electron traps, degrading the electron field-emission properties of β-Ga₂O₃ nanobelts.     

Nanostructured alignment layer for liquid crystals

A new type of nanostructured alignment surface is proposed and demonstrated. As in previous nanostructured alignment surfaces, a large pretilt angle of near 45° can be produced reliably. Moreover, this new structure is fabricated with a mask, and there is no randomness involved. The uniformity and anchoring properties of this new surface have been measured to be of excellent quality.     

Facilitation of consumer loyalty toward branded applications: The dual-route perspective

Although many brands develop mobile applications (apps) to build relationships with consumers, most branded apps fail to retain consumers’ loyalty. This study examines the facilitation of consumer loyalty toward branded apps (continuance intention, in-app purchase intention, and word-of-mouth intention) from the dual-route perspective. One route is the affective (relationship) route, where brand benefits (functional benefits, experiential benefits, symbolic benefits, and monetary benefits) drive parasocial interactions between consumers and the brand, which, in turn, influences branded app loyalty. The other route is the utility route, where system characteristics (system quality and information quality) affect perceived usefulness, which, in turn, facilitates branded app loyalty. An online survey was conducted, and the research model was empirically tested using partial least squares structural equation modeling. The findings support the dual-route perspective according to which both affective and utilitarian paths facilitate branded app loyalty. The key theoretical contribution of this study is that it moves beyond the utilitarian path and finds the affective (relationship) path to give a more complete picture of the facilitation of consumer loyalty in the branded app context. A strategy is provided to suggest to practitioners how to design branded apps to facilitate consumer loyalty.     

α-Alumina and spinel react into single-phase high-alumina spinel in <3 seconds during flash sintering

In situ X-ray diffraction measurements at the Advanced Photon Source show that α-Al₂O₃ and MgAl₂O₄ react nearly instantaneously and completely, and nearly completely to form single-phase high-alumina spinel during voltage-to-current type of flash sintering experiments. The initial sample was constituted from powders of α-Al₂O₃, MgAl₂O₄ spinel, and cubic 8 mol% Y₂O₃-stabilized ZrO₂ (8YSZ) mixed in equal volume fractions, the spinel to alumina molar ratio being 1:1.5. Specimen temperature was measured by thermal expansion of the platinum standard. These measurements correlated well with a black-body radiation model, using appropriate values for the emissivity of the constituents. Temperatures of 1600-1736°C were reached during the flash, which promoted the formation of alumina-rich spinel. In a second set of experiments, the flash was induced in a current-rate method where the current flowing through the specimen is controlled and increased at a constant rate. In these experiments, we observed the formation of two different compositions of spinel, MgO•3Al₂O₃ and MgO•1.5Al₂O₃, which evolved into a single composition of MgO•2.5Al₂O₃ as the current continued to increase. In summary, flash sintering is an expedient way to create single-phase, alumina-rich spinel.     

An optimal volute spiral case design for centrifugal fan: theoretical and experimental studies

An inverse design problem in determining the optimal shape of volute spiral case for a centrifugal-flow fan is examined in the present study using the Levenberg–Marquardt method and a general purpose commercial code CFD-ACE+, and based on a desired airflow rate. The desired volume airflow rate can be obtained by multiplying the airflow rate of an existing fan by a constant number which is >1. The shape of the redesigned volute case is generated using the equation of the trajectory of fluid particles in the volute, which enables the shape of the fan volute be constructed completely. Finally, prototypes of the original and optimized fan volutes as well as fan impellers are fabricated, thereafter the fan performance is tested based on the AMCA-210-85 standard to verify the validity of the design. The experimental results demonstrate that by utilizing the fabricated centrifugal optimal fan and operating at the design condition, the airflow rate can be increased by 6.5 % and the pressure drop, noise and input power of fan can be reduced by 1.6, 5.3 and 11.4 %, respectively, when compared with the original fan. As a result, the performance of optimal fan can be improved greatly.     

A Multivariate EWMA Controller for Linear Dynamic Processes

Most research of run-to-run process control has been based on single-input and single-output processes with static input–output relationships. In practice, many complicated semiconductor manufacturing processes have multiple-input and multiple-output (MIMO) variables. In addition, the effects of previous process input recipes and output responses on the current outputs might be carried over for several process periods. Under these circumstances, using conventional controllers usually results in unsatisfactory performance. To overcome this, a complicated process could be viewed as dynamic MIMO systems with added general process disturbance and this article proposes a dynamic-process multivariate exponentially weighted moving average (MEWMA) controller to adjust those processes. The long-term stability conditions of the proposed controller are derived analytically. Furthermore, by minimizing the total mean square error (TMSE) of the process outputs, the optimal discount matrix of the proposed controller under vector IMA(1,?1) disturbance is derived. Finally, to highlight the contribution of the proposed controller, we also conduct a comprehensive simulation study to compare the control performance of the proposed controller with that of the single MEWMA and self-tuning controllers. On average, the results demonstrate that the proposed controller outperforms the other two controllers with a TMSE reduction about 32% and 43%, respectively.