The Role of E-mail Communications in Determining Response Rates and Mode of Participation in a Mixed-mode Design

© The Author(s) 2017. This article is concerned with the extent to which the propensity to participate in a web face-to-face sequential mixed-mode survey is influenced by the ability to communicate with sample members by e-mail in addition to mail. Researchers may be able to collect e-mail addresses for sample members and to use them subsequently to send survey invitations and reminders. However, there is little evidence regarding the value of doing so. This makes it difficult to decide what efforts should be made to collect such information and how to subsequently use it efficiently. Using evidence from a randomized experiment within a large mixed-mode national survey, we find that using a respondent-supplied e-mail address to send additional survey invites and reminders does not affect survey response rate but is associated with an increased proportion of responses by web rather than face-to-face and, hence, lower survey costs

Zero voltage switching used for a reversible DC-DC converter

Abstract A novel bi-directional dc-dc converter with Zero Voltage Switching (ZVS) and interleaving for dual voltage systems in automobiles is presented. A variable frequency extended band hysteretic current control method is proposed. In comparison with classical fixed frequency current control PWM, the reverse polarity peak current needed for ZVS operation is kept constant. Inductor current ripple decreases with load reduction. Automatic changes in operation between buck and boost modes are accomplished without transient currents. Converter simulations are carried out using Matlab/Simulink platform

Measurement Equivalence in Sequential Mixed-Mode Surveys

Many surveys collect data using a mixture of modes administered in sequential order. Although the impacts of mixed-mode designs on measurement quality have been extensively studied, their impacts on the measurement quality of unobservable (or latent) constructs is still an understudied area of research. In particular, it is unclear whether latent constructs derived from multi-item scales are measured equivalently across different sequentially-administered modes—an assumption that is often made by analysts, but rarely tested in practice. In this study, we assess the measurement equivalence of several commonly-used multi-item scales collected in a sequential mixed-mode (Web-telephone-face-to-face) survey: the Age 25 wave of the Next Steps cohort study. After controlling for selection via an extensive data-driven weighting procedure, a multi-group confirmatory factor analysis was performed to assess measurement equivalence across the three modes. We show that cross-mode measurement equivalence is achieved for nearly all scales, with partial equivalence established for the remaining. Although measurement equivalence was achieved, some differences in the latent means were observed between the modes, particularly between the interviewer-administered and selfadministered modes. We conclude with a discussion of these findings, their potential causes, and implications for survey practice

Analytical design and analysis of line-start permanent magnet synchronous motors

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Harmonic minimization in modulated frequency single-phase matrix converter

Abstract: This Field Programmable Gate Array (FPGA) based digital controller has been developed to improve the output of the frequency converter using Hardware Description Language. An attempt has been made to analyze converters using three modulation techniques namely sinusoidal pulse width modulation (SPWM), delta modulation (DM) and trapezoidal modulation (TM) to reduce the harmonics. It has been found that for the Sine PWM, the total harmonic distortion factor (THD) is high when the output frequency is greater than input frequency. The output is improved with delta modulation scheme where the total harmonic distortion is found minimum as compare to the SPWM and TM techniques. The circuit has been tested qualitatively by observing various waveforms on digital storage oscilloscope (DSO). The overall system is compact and no external memory system is required. Tests have been carried out to show the effectiveness and flexibility of the proposed method

Comparative analysis of modulation techniques in frequency converter

Abstract: A generalized frequency converter has been realized which makes use of a cyclo-converter in newer form AC-AC converter. An attempt has been made to operate this converter both in a conventional low frequency AC-AC converter and a new high frequency AC-AC converter. The ability to directly affect the frequency conversion of power without any intermediate stage involving DC power is a huge advantage of the system. The output of this converter has a frequency either fo = fi × Nr or fo = fi / Nr. where Nr is an integer and fi is the source frequency. A methodology is developed to generate the required trigger signal for any integer multiple/sub multiple of the output frequency. The undesirable harmonic components in the output of the frequency converter have been minimized using four modulation techniques namely; sinusoidal pulse width modulation (SPWM), delta modulation (DM), trapezoidal modulation (TM) and space vector modulation (SVM) technique. The converter is simulated using well known software package MATLAB. Comparative simulation analysis is presented for a single phase frequency converter (SPFC) topology with all these modulation techniques when the converter is operating both step up as well as for step down mode

Towards 'Trade Policy Analysis 2.0': From National Comparative Advantage to Firm-Level Trade Data

This paper makes the case for the need to "upgrade" current analytical tools used for trade policy analysis and complement them with more detailed firm-level data. Such an upgrade should be based on the latest intellectual advancements in trade theories and the latest firm-level trade statistics that are now becoming widely available. An upgraded "Trade Policy Analysis 2.0" could contribute to several trade policy priorities and to a better understanding of the benefits from international trade for firm competitiveness, job creation, and consumer welfare

The Role of Email Communications in Determining Response Rates and Mode of Participation in a Mixed-mode Design

This article is concerned with the extent to which the propensity to participate in a web-face-to-face sequential mixed-mode survey is influenced by the ability to communicate with sample members by email in addition to mail. Researchers may be able to collect email addresses for sample members and to use them subsequently to send survey invitations and reminders. However, there is little evidence regarding the value of doing so. This makes it difficult to decide what efforts should be made to collect such information and how to subsequently use it efficiently. Using evidence from a randomized experiment within a large mixed-mode national survey, we find that using a respondent-supplied email address to send additional survey invites and reminders does not affect survey response rate but is associated with an increased proportion of responses by web rather than face to face and, hence, lower survey costs

Analiza efectului clinic al aplicării unguentului „Argidină” efectuat în Centrul Republican de leziuni termice

Catedra Ortopedie - Traumatologie şi Сhirurgie în Campanie a USMF "Nicolae Testemitanu”The analysis of obtained clinical results after application of ”Argidina” salve demonstrates its high efficacy in treatment of superficial and profound burns of reduced surfaces. The ”Argidina” salve diminishes the colonies of infection, the bandage is atraumatic, creates optimum conditions of wound regeneration in case of burns of II-IIIAB grade, of sectors of donor wounds