Front Stage Research Articles

Research on Cascaded On‐Board DC/DC Converter Based on Three‐Phase Interleaved LLC

ABSTRACTThe on‐board DC/DC converter proposed in this research consists of a Buck converter and a three‐phase interleaved LLC resonant converter. This paper analyzes the average current and output current ripple characteristics of the rear‐stage converter in addition to explaining the topology and working principles of the front‐stage Buck converter and the rear‐stage three‐phase interleaved LLC resonant converter. To establish a single‐phase fundamental equivalent circuit for the rear‐stage converter, apply the fundamental wave analysis method, and it is essential for comprehending the impact of relevant system parameters on voltage gain characteristics and resonant operating regions. Conducting research on the two‐stage on‐board DC/DC converter's control strategy involves establishing small‐signal circuit models for both front and rear stage converters, derivation of parameters for double closed‐loop control, and determination of the control strategy employing phase‐shifted current sharing for the rear‐stage converter in cases where significant tolerance exists in resonant components. The simulation for a two‐stage on‐board DC/DC converter results indicates that under various conditions of resonant component tolerance, the converter is capable of achieving balanced phase currents and demonstrates minimal output current ripple prior to capacitor filtering. A 1.5‐kW experimental prototype has been fabricated, and the experimental findings indicate that the output voltage remains stable at 13.8 V despite fluctuations in input voltage. The highest efficiency of the prototype is about 96.27%, and the utilization of phase‐shifting current balancing control results in a notable reduction in output current ripple. This provides more evidence that the design of a two‐stage on‐board DC/DC converter is correct.

Managing impressions: performance and identity in police leadership in the pandemic

ABSTRACT Critical leadership scholars have long recognised leadership as performative and reveal the symbolic, presentational and ritual aspects of leadership practice as meaning-making. This perspective, however, is neglected in mainstream understanding of police leadership. Drawing on Goffman’s dramaturgical framework and a qualitative study of policing leaders in the UK, this paper explores performativity and police leadership in the context of the COVID-19 pandemic. Removed from occupational symbols of the police station and performing leadership work exclusively in the home environment, the findings show that police leaders used the uniform as part of a strategy of impression management to construct front and back stage regions in the domestic sphere. In frontstage settings, the uniform was used to represent occupational authority and reinforce a sense of shared, professional identity and purpose, despite the physical separation between leaders and their staff. Alongside this, police leaders constructed and maintained backstage spaces for preparatory and reparative work, even within the home-working setting. The findings challenge traditional conceptualisations of the backstage as physical, boundaried space of the police station and instead reveal backstage space as fluid, dynamic and imagined. As police constabularies consider the impact of remote-working practices on the police workplace, the preservation of backstage spaces for police leaders during the COVID-19 pandemic reveals the value and necessity this backstage work in police leadership.

Dramaturgical Analysis of Role-players on Telegram

K-Pop (Korean Pop) culture is very popular among Indonesian people, especially children and teenagers. One of the impacts of the popularity of K-Pop is the emergence of role-play accounts. Role-play is a make-believe game that requires players to imitate a K-pop idol. Someone who plays role-play will be called a role-player. We aimed to analyze the differences between how a role-player act in the role-play world and the real world. This research focuses on Telegram role-players. We applied a qualitative netnographic research design and used a dramaturgical theory as a research approach. The results of this study showed that the role-players used Telegram as their front stages where they managed the impressions according to the role-play personas they chose. In addition, the results of this research showed that the direct message features of the role-players’ Telegram accounts are used as their middle stages while the backstage is their real life. The results suggest that each role-player has a different character from their role-play persona, showing the distinctive differences among the front stage, the middle stage and the backstage.

Optimizing Electric Vehicle Performance: Advances in Battery Management Systems for Enhanced Efficiency and Longevity

The management of electric car batteries has taken front stage in automotive research and development as more people choose electric vehicles (EVs). Optimal performance, safety, and lifetime of electric vehicles depend on effective battery management systems (BMS). To address this, we developed software for system functionality testing and a BMS prototype with an AVR ATmega family micro-controller. The originality of this work is the practical application of Arduino platform for BMS development, offering a scalable and reasonably priced solution that goes beyond past efforts by including the most recent technological developments and addressing modern challenges in the field. Conclusions drawn show that overcoming present battery performance constraints by developing BMS technology will open the path for more general EV acceptance.

Praktik Keagamaan Pekerja Seks Komersial dalam Kehidupan Bermasayarakat pada Kawasan Medan Tuntungan Simpang Selayang

The purpose of this study is to reveal the religious practices carried out by prostitutes. This study is a qualitative descriptive study. The data collection methods used are interview methods, observation methods and documentation methods. The results of the study show that: First, the choice to enter the world of prostitution is a materialistic demand that must be met, which usually comes from a broken home and as a widow or someone who is responsible as the backbone of the family. Second, for prostitutes, the job is tempting, and can empower families and improve the economy. The results of the study show that being a prostitute does not make them non-religious people. They even realize that the profession they do is a sin, even so they do not blame God for what happened to them. They believe that what they do is due to coercion due to materialistic demands that they must fulfill and hope that God will forgive their actions. Besides that, if viewed from the Dramartugi theory related to the front and back stage of a sex worker, almost all sex workers play a role, when they become sex workers they act according to their profession, namely by dressing up, wearing sexily, speaking gracefully, with the aim of seducing customers while on the other hand, when at home they behave normally like society in general.

Application and practice of portable bi-directional DC-AC energy storage converter based on second order generalized integrator phase-locked loop and HERIC circuit

In various industries, including the production of new energy and electric vehicles, portable bidirectional converters are crucial for enhancing power supply reliability. In recent years, these converters have become increasingly normal in daily life. Bidirectional converters have not been as popular or have not been used as much due to issues with phase tracking on grids connected to leakage current in the converter system. The essential features and principles of the portable bidirectional energy storage converter proposed in this paper, which is based on a second-order generalized integrator phase-locked loop, are theoretically investigated. Formulas are also generated using small signals to address this issue. PLECS simulation software was used for parameter design and algorithm simulation to test the effectiveness of the phase-locked loop under various operating situations. Therefore, a set of appropriate phase-locked structure models for this circuit was developed. An experimental verification platform was constructed to confirm the accuracy of the design parameters: the front stage uses the H-bridge; the backstage, which uses the front stage, adopts the H-bridge; and the rear stage adopts the topology platform of the HERIC topology + LCL filter circuit. The test data indicates that, the addition of the HERIC topology and soft switching resulted in a 94 % reduction in leakage current and a 1.6 % improvement in efficiency. Analysis and comparison results of the test data confirmed the consistency between the experimental effect and the design parameters, achieving the expected effect and proving the accuracy of the topology and mathematical model. The design methodology and design parameters of this thesis are useful and instructive for similar or related research.

Analisis Dramaturgi Dalam Film Dear David

Film is a medium of learning for the audience that is not only an entertainment, it can also convey direct messages through images, dialog and plays. Netflix has become one of the global streaming platforms that can be accessed in Indonesia since 2016. Dear David is a Netflix original movie in the genre of romantic fantasy drama that airs in 2023 directed by Lucky Kuswandi. The movie Dear David received a lot of debate, because this movie contains sexual fantasies in women. This research aims to find out how the dramaturgical analysis in the movie Dear David. The method used is a qualitative approach using Charles Sanders Pierce's semiotic analysis technique through three stages, namely representamen, object and interpretation. Each scene of the film illustrates that there is dramaturgy in the film Dear David through several scenes, namely heterosexuality, women are free to choose how to enjoy their freedom according to their respective tastes and styles. Femenism is that women have power that is arbitrary towards others and self-acceptance is a form of being able to accept their identity and respect others. The results of this study show that the dramaturgy in the film Dear David is depicted by the main character Laras that the story of the film Dear David shows the existence of a front stage showing her as an outstanding high school student and a back stage as a child with heterosexual sexual fantasies as evidenced by having a privacy fantasy blog. Overall, this movie provides an overview of the dramaturgical approach not what is done, but the reasons for how it can be done.

The United States as a ‘Pacific Nation’: Imaginary, Performance, and Spatialisation

ABSTRACT In 2012, then United States (US) Secretary of State Hilary Clinton attended the leaders’ meeting of the Pacific Islands Forum, the region’s pre-eminent politics and security-focused multilateral institution. At the meeting, Clinton remarked that: ‘I have said that the 21st century will be America’s Pacific century, with an emphasis on Pacific’, as the US is ‘a Pacific nation’. In this article, we analyse how, in the decade since, US government discourse has continued to narrate a social imaginary of the US as a ‘Pacific nation’ and to attempt to bring that imaginary into being through diplomatic performances and government policy. This has been driven by strategic concerns about the increasing activism of China in the Pacific Islands region and has sought to justify the US’s role, build its relationships, and exercise its power in the region. We argue that when the US is front stage and conscious of being observed, it narrates an imaginary of itself as a Pacific nation and performs that imaginary through its diplomatic performances and policy announcements. But the US’s back stage behaviour, including the non-implementation of policies and the spatialisation of the Pacific Islands region through efforts to discipline Pacific Island countries, build boundaries that exclude China, and emplace the US military presence, reveals its true intentions.

Effect of inlet distortion on internal flow and performance of a contra-rotating fan operating with single-stage impeller

To establish a theoretical foundation for the rational selection of contra-rotating fans operating with a single-stage impeller under inlet distortion. Unsteady numerical simulations were conducted using the SST k-ω turbulence model to analyze the airflow fields, respectively, for the single-stage operation of front impeller (SSOFI) and the single-stage operation of rear impeller (SSORI) of the fan. The internal flow characteristics with single-stage operation under both distorted inlet condition (DIC) and uniform inlet condition (UIC) were studied. Furthermore, a comparison of the performance parameters of the fan, including total pressure and total pressure efficiency, was conducted. Focusing on the SSOFI with satisfactory operational performance of the contra-rotating fan, this study aims to reveal the propagation of inlet distortion inside the fan and reveal the influence mechanisms of inlet distortions on the performance of the fan. The results indicate that the impact of inlet distortion on the flow field is primarily concentrated in the upstream area of the front-stage impeller for SSOFI. However, the flow disturbance from the exit of the front-stage impeller to the diffuser is relatively minimal. For SSORI, the inlet distortion exacerbates the adverse effect of the front stage impeller as the front guide vane on the flow inside the rear stage impeller. The entropy loss in the two-stage impellers is significantly higher than that under the uniform inlet condition, and the turbulence level in the diffuser is intensified. While the efficiency of the fan is significantly influenced by the inlet condition and operating stages, their impact on the total pressure is small. Specifically, under uniform inlet conditions, the total pressure efficiency for SSOFI exceeds that of SSORI by 4.9 %, whereas the difference rises to 11 % under inlet distortion condition.

Compact hundred-watt level picosecond laser system based on tapered double cladding fiber-single crystal fiber hybrid amplifier

This paper introduces a compact picosecond laser system using tapered double cladding fiber-single crystal fiber hybrid amplification technology for the first time. By modifying the Ginzburg-Landau equation, we established a simulation model and designed a passive mode-locked picosecond oscillator based on a semiconductor saturable absorber mirror. The oscillator outputs laser with a pulse width of 7.75 ps, a center wavelength of 1030.55 nm, and a spectrum width of 0.58 nm. The seed laser is stretched and amplified by the all-fiber front stage, and then injected into the tapered double cladding fiber-single crystal fiber hybrid amplifier. The laser power is amplified from 820 mw to 103.1 W, obtaining a gain of 21 dB. We used zero-phonon line pumping technology in single crystal fiber amplifier to reduce the thermal effects caused by quantum loss, thereby increasing the length of the crystal and increasing the power loading capacity. We designed a single crystal fiber amplification module using Yb:YAG with 60 mm long, 1 mm diameter and a 1 at.% doping rate for the first time. Finally, a hundred-watt level picosecond laser output with a repetition frequency of 26.33 MHz, an average power of 103.1 W, a pulse width of 244.72 ps, a spectrum width of 1.16 nm, and a beam quality of M2 x = 1.368 and M2 y = 1.511 was obtained. To the best of our knowledge, this is the highest picosecond laser output power for an all-fiber front-stage combined with a single-stage single crystal fiber amplifier.

Dramaturgy of Cirebon Teenage Consumer Behavior in Building Self-Image on Instagram

Instagram is just one of several social media programmes made possible by the latest developments in digital technology. Instagram is more than just a virtual communication tool, but helps teenagers also build their self-image through its many functions. This study aims to uncover how Cirebon teenagers' self-image building works on Instagram, as well as their purchasing habits. The research methodology, particularly the qualitative approach. Results were obtained from an extensive literature review, in-depth interviews, and participant observation. Erving Goffman's dramaturgical perspective was used to examine the data obtained. Teenagers in Cirebon use Instagram as a dramaturgical tool to shape their self-image, according to the research conclusion. Their front stage consistently displays positive aspects and the best material, helping them cultivate a positive self-image and get positive reactions from fans. In addition, Instagram users' real lives are very different from their Instagram appearances, and often users do not want other users to know the ins and outs of their personal lives, including the steps used to create their Instagram appearances.

Cpa-free Yb:YAG thin-disk regenerative amplifier laser with hundreds of watts, hundreds of kHz, and hundreds of picoseconds

This paper introduces a CPA-free Yb:YAG thin-disk regenerative amplifier laser system. The seed pulse is generated by a passive mode-locked picosecond oscillator based on a semiconductor saturable absorber mirror, with a center wavelength of 1030.7 nm, a pulse width of 7.7 ps, and a repetition frequency of 26.3 MHz. After stretched and pre-amplified by an all-fiber front stage, the seed with a pulse width of 201.3 ps and a pulse energy of 15.2 nJ was obtained, then injected into the thin-disk regenerative amplifier. Yb:YAG crystal was chosen as the material for the thin-disk, with 100 μm thickness, 9 mm diameter and 7 at.% doping rate. In order to increase the one-way round-trip gain of the thin-disk regenerative amplifier, a symmetrical dual-pass resonant cavity was designed to double the number of passing through the crystal on a round trip in the regenerative resonant cavity to reduce the times of cycles, intra-cavity loss and improve optical efficiency. We used a 969 nm fiber-coupled semiconductor laser as the pump source to pump the Yb:YAG thin-disk crystal. With zero-phonon line pumping technology, the quantum loss and thermal effect were reduced. In the end, we obtained a regenerative amplification output with an average power of 104.5 W, a repetition frequency of 200 kHz, a pulse width of 143.9 ps, and a spectrum width of 0.39 nm. The amplified pulse had quite good beam quality with Mx2 = 1.09 and My2 = 1.14.

Design and analysis of soft-switching and small-signal model grid-connected micro-inverter based on staggered parallel connection

Grid-connected micro-inverters, known for their straightforward wiring and operational stability, have garnered increasing interest from both industry and academia. However, the operational inefficiency of conventional inverters, the issue of distorted output waveforms, and the safety concerns with alternating current (AC) and direct current (DC) safety isolation limit the wide availability and utilization of micro-inverters. In order to overcome this problem, this research proposes a circuit topology consisting of two flyback circuits connected in parallel on the primary side of the transformer for safe isolation. Additionally, soft switches are incorporated into the flyback circuit at the front stage, with a voltage total harmonic distortion (THD) of less than 3.0 %. This study also develops a small-signal model to help with obtaining the current loop parameters. Parametric design and simulation studies with PLECS software confirmed the circuit architecture and control technique's accuracy. A 600 W prototype's design, analysis, and experimental validation are described. The proposed inverter has an efficiency of up to 97.2 %. The design and control methods employed in this paper offer a conceptual framework and engineering reference for relevant research and practical applications.

Correlation of tumor-associated macrophage density and proportion of M2 subtypes with the pathological stage of colorectal cancer.

Colorectal cancer (CRC) is a prevalent global malignancy with complex prognostic factors. Tumor-associated macrophages (TAMs) have shown paradoxical associations with CRC survival, particularly concerning the M2 subset. We aimed to establish a simplified protocol for quantifying M2-like TAMs and explore their correlation with clinicopathological factors. A cross-sectional study included histopathological assessment of paraffin-embedded tissue blocks obtained from 43 CRC patients. Using CD68 and CD163 immunohistochemistry, we quantified TAMs in tumor stroma and front, focusing on M2 proportion. Demographic, histopathological, and clinical parameters were collected. TAM density was significantly higher at the tumor front, with the M2 proportion three times greater in both zones. The tumor front had a higher M2 proportion, which correlated significantly with advanced tumor stage (P = 0.04), pathological nodal involvement (P = 0.04), and lymphovascular invasion (LVI, P = 0.01). However, no significant association was found between the M2 proportion in the tumor stroma and clinicopathological factors. Our study introduces a simplified protocol for quantifying M2-like TAMs in CRC tissue samples. We demonstrated a significant correlation between an increased M2 proportion at the tumor front and advanced tumor stage, nodal involvement, and LVI. This suggests that M2-like TAMs might serve as potential indicators of disease progression in CRC, warranting further investigation and potential clinical application.

Transonic Compressor Darmstadt Open Test Case: Experimental Investigation of Stator Secondary Flows and Hub Leakage

Abstract The future trend of clean sky aviation has led to a smaller core engine, resulting in highly loaded stages with increased relative tip gaps and leakage flows, which causes a reinforced influence of secondary flow phenomena. This article experimentally investigates the secondary flow effects in the 3D-optimized shrouded stator of the TUDa-GLR-OpenStage, representative of a transonic high-pressure compressor front stage, and its susceptibility to typical hub leakage flows. The impact of stator hub leakage on efficiency and total pressure ratio is investigated for several operating speeds, from subsonic to nominal transonic operating conditions. Steady five-hole probe and time-resolved virtual multi-hole probe measurements at different operating conditions at nominal speed are conducted to investigate the underlying loss mechanisms. The leakage mass flow is determined using the measured pressure difference within the fin seal. Steady results show that the optimized 3D stator effectively suppresses the hub corner separation compared to the predecessor 2D stator, but its performance is further limited by a near-tip separation. With the increased stator hub leakage (at a leakage-to-main flow ratio of about 0.4%), the compressor isentropic efficiency generally drops (by about −0.5%) at the full operating range due to an enhanced hub corner separation effect. However, the increased leakage also helps alleviate the tip-corner separation when operating near stall, leading to a smaller efficiency penalty under these conditions. Unsteady results reveal the sensitivity of transient compressor performance to the passing rotor wake, but limited interaction between this phenomenon and the increased leakage is observed. These findings provide insight into the stator hub leakage-related penalties on the compressor aerodynamics efficiency.

Design and Experiment Verification to Combined Dynamic Seal of Wide-Speed Hydraulic Motor Pump

To reduce the wear of lip seal of wide-speed hydraulic motor pump and prolong the service life, the lip compression is reduced and the non-contacting labyrinth seal is used as the front stage, forming a series combined dynamic seal (CDS). The reliability of CDS in the wide-speed range is verified by model experiment. Initially, the structure form and dimension of labyrinth seal with relatively small leakage and heat production were determined by model experiment. Then, by establishing the model of lip seal and simulating the static structure, the relationship between the compression and maximum contact pressure of the lip was obtained. Finally, using the CDS which is formed by combining the different lip seals with the selected labyrinth seal to carry out experiments, the leakage, temperature distribution and lip wear were obtained. The results show that trapezoidal tooth labyrinth seal (TTLS) has better sealing effect and less heat production. When the sealing clearance is 0.1 mm and 0.3 mm, it accounts for 0.11% and 0.32% of the rotor diameter, respectively. Under the same conditions, the smaller the proportion, the better the sealing effect, but the higher the heat production. With the increase of compression, the maximum sealing pressure first increases and then decreases. When the compression of the lip exceeds 0.1 mm, the CDS will not leak significantly in a wide-speed range, but the greater is the compression, the faster is the temperature rise in the closed cavity. Lip wear is positively correlated with pv and the wear decreases with the decrease of compression.

Student Social Conflict Dramaturgy at Universitas Muhammadiyah Makassar

This research aims to analyze and describe the occurrence of student conflict dramaturgy at Muhammadiyah University Makassar, to analyze and synthesize the mechanism of the student conflict dramaturgy process at Muhammadiyah University Makassar, and to design solutions for student conflict dramaturgy Unismuh Makassar. This type of research is qualitative research with a case study approach. The informants for this research were 22 informants. Data was found through field observations, in-depth interviews, and documentation. These data are developed by giving meaning to the data, interpreting, or transforming the data into narrative forms which then lead to findings that nuanced scientific propositions that ultimately reach conclusions. Based on the results of the analysis, it was found that student conflict dramaturgy was developed by the interests of alumni actors, self-actualization, regional symbols, individual differences, and even clashes of interests. The dramaturgical process of student conflict was based on the front stage, then the middle stage continues to the backstage, then normal activities (of Stage) and forms of conflict dramaturgy including, inter-individual conflict, inter-group conflict, political conflict, and the last one is the dramaturgical solution to student conflict at the Muhammadiyah University of Makassar through an emotional approach, mediation, and providing space for actor actualization.

Research on Electro-hydraulic Servo Valve Structure and Control Algorithm of System with Servo Valve

Background: With the continuous progress of electronic information technology, people have begun to study the combination of electronic information technology and hydraulic technology to achieve more accurate and flexible control. Electro-hydraulic servo technology was thus developed. Much attanetion has been paid to electro-hydraulic servo valve,a key component of electrohydraulic servo technology. Objective: The number of stages of the electro-hydraulic servo valve, the structure form of the electro- hydraulic servo valve hydraulic front stage, the feedback form of the electro-hydraulic servo valve, the output form of electro-hydraulic servo valve, and the control algorithm based on the application of electro-hydraulic servo valve are analyzed and commented respectively. Combined with associated patents, the research direction and hot topics of electro-hydraulic servo valves are analyzed. Method: The electro-hydraulic servo valves were briefly classified; and then the problems of different types of valves were discussed in depth. Results: By analyzing the problems of electro-hydraulic servo valves, the problems of how to improve the control accuracy, response speed, anti-interference ability, service life and cost reduction of electro-hydraulic servo valves are analyzed comprehensively, and the future development prospect of electro-hydraulic servo valves is predicted and outlooked. Conclusion: Analyzing and discussing the existing hot issues of electro-hydraulic servo valves helps to update and change the electro-hydraulic servo valves, and makes corresponding references for the subsequent research of electro-hydraulic servo valves.

CASTING A DIGITAL SPELL: HOW SOCIALMEDIAINFLUENCERS SHAPE DESTINATION MARKETING

In a time when social media has taken the front stage, the travel and tourism industry has changed dramatically. The development of social media influencers as important players in destination marketing has been a major driving force behind this change. This essay aims to explore the significant impact these digital trendsetters have on destination marketing. It explores the strategies and achievementsof influencer marketing efforts, demonstrating how these digital pioneers are changing the travel landscape and impacting the choices made by travelers. To investigate the impact of influencer marketing and provide a summary of studies in these areas, a review of the literature was conducted as part of this study.

The pronunciation of students’ names in higher education: identity work by academics and professional services staff

ABSTRACT Changes in the national, linguistic and ethnic profiles of students in UK higher education mean that students’ names are also likely to have become increasingly culturally diverse. In this article, we develop new empirical and theoretical understandings about how student-facing staff working in higher education in England experience cultural diversity in students’ names and the accompanying uncertainty of how some names should be pronounced. Using data from our qualitative studies we show that staff typically framed the pronunciation of names as an equalities issue, including in terms of power relations between themselves and students. Drawing on theorisations of identities as social processes, we analyse the ‘front stage’ and ‘backstage’ activities used by staff to manage the pronunciation of students’ names. We argue that, through these equality-framed activities, staff are doing ‘identity work’ in relation to their own selves and, importantly, also for students whose named-linked identities are minoritised within the ‘whiteness’ and ‘Englishness’ of higher education institutions in England. We conclude that, to support the pioneering identity work already undertaken by individual staff, policymakers in higher education should develop and implement ‘whole institution’ initiatives in recognition of the pronunciation of students’ names as a key equality, diversity and inclusion issue.