여성사 쓰기의 가능성과 현주소, 한국여성연구소 여성사연구실 지음, 청년사 1999

textIn the midst of the turbulence wrought by the global economy, it has become common to see projects as an essential medium for achieving change. However, project based learning practices - as a subset of organizational learning practices- have not kept pace with this development. To explore this concern, we have carried out a study on practices adopted by organizations for learning through projects involving nineteen companies from across Europe and from a range of different industries. We use the concepts of variation, selection and retention in organizational learning to analyze our findings and report the challenges faced by project based organizations in each of the areas highlighted. We conclude that time pressures, centralization and deferral are the key characteristics of learning in project based firms and that these impede project based members in learning from and through projects.

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Quantity versus Quality in Project Based Learning Practices

Future smart battery and management: Advanced sensing from external to embedded multi-dimensional measurement

Communication technologies for smart grid applications

Despite being a well-established ingredient to many wireless systems, multiple-input–multiple-output (MIMO) signal processing has only recently been considered for broadband power line communications (PLC). Adapting multiple-antenna transmission and reception techniques to a wired medium such as the electrical grid requires solving a number of issues, both regarding the physics of electromagnetic transmission and the optimization of the signal processing strategies. In the last few years, significant steps were made to demonstrate the benefits of MIMO PLC and to develop the necessary hardware. As a result, MIMO PLC has been adopted in several broadband PLC specifications, precisely as part of ITU-T G.hn in Recommendation G.9963, and as part of the industry specification HomePlug AV2, which is backward compatible to IEEE 1901. This paper reviews important aspects of MIMO PLC, highlighting its similarities and main differences with classical wireless MIMO. It focuses first on the peculiarities of the electrical grid, with a survey of PLC channel and noise characterization in a MIMO context. It further estimates MIMO PLC channel capacity adhering to the electromagnetic compatibility regulations currently in force. In addition, MIMO signal processing techniques most suited to PLC environments are discussed, allowing for throughput predictions. It is found that eigenbeamforming is the best choice for MIMO PLC: the full spatial diversity gain is achieved for highly attenuated channels, and maximum multiplexing gain is achieved for channels with low attenuation by utilizing all spatial streams. It is shown that upgrading from a conventional single-input–single-output PLC configuration to a 2 $\times$ 2 MIMO configuration, the throughput can be more than doubled while coverage is increased. The survey concludes with a review of specific MIMO PLC system implementations in the specifications ITU-T G.9963 and HomePlug AV2.

/pdf/mimo-power-line-communications-4ne3jmejfj.pdf

MIMO Power Line Communications

In-vehicle power line communication (PLC) holds great promises as an enabler of in-vehicle communication without increasing weight, volume, or cost of the wiring harnesses. In this paper, we join a few recent works and present channel measurements for a specific compact car. We discuss and compare our measurement results with those obtained in previous campaigns. Furthermore, we evaluate our measurements from the viewpoint of high connectivity. That is, we are interested in the suitability of PLC for applications that require a reliable link from any node to any other node at any time. Perhaps not surprisingly, we find that advanced transmission techniques such as multihop or frequency diversity are necessary to achieve this goal.

/pdf/measurement-study-and-transmission-for-in-vehicle-power-line-io1y3yy1j4.pdf

Measurement study and transmission for in-vehicle power line communication

Bounded uncorrelated jitter (BUJ), a subcomponent of total jitter, is commonly caused by crosstalk coupling from adjacent interconnects on printed circuit boards (PCB). However, the characteristics of BUJ are still not well understood. Neither a mathematical model of jitter, nor an algorithm to generate histograms for BUJ has been developed to this date. Such a model and algorithm would empower designers to predict BUJ to achieve total jitter budget without lengthy simulations and measurements. In this paper, we first review the characteristics of a crosstalk pulse induced by an aggressor signal on a quiet trace. Then, by applying the superposition principle, a jitter model to calculate the time difference between the distortion-free and the distorted edge crossings of the victim signal was developed. This model is also extended to calculate the worst case timing difference, BUJ/sub p-p/. In addition, an algorithm to generate the histogram distribution of BUJ is also developed. The developed algorithm has fast execution times of 10-20 s, compared to simulation and measurement times of 10-30 min.

Crosstalk bounded uncorrelated jitter (BUJ) for high-speed interconnects

In today's electric and conventional combustion engine vehicles, data communication between electronic control units is accomplished by sending communication signals over dedicated wires. The space requirement, weight, and installation costs for these wires can become significant, especially in electric vehicles (EVs) of the future, which are highly sophisticated electronic systems. The concept of reusing existing electricity wires, which are needed to power electronic components, for data communication, i.e., vehicular power line communications (V-PLC), is thus a promising means to reduce the amount of dedicated wiring and/or establish redundant communication buses especially for EVs. Previous work on V-PLC has mostly focused on combustion engine vehicles. In this paper, we present the methodology and results from a measurement campaign with the goal of characterizing the transmission conditions for V-PLC in a hybrid EV (HEV). Emphasis is given to the choice of measurement points (potential nodes of a V-PLC network) and the proper design of adapters for measurement equipment. The results presented here focus on channel transfer function and access impedance.

Channel characterization for power line communication in a hybrid electric vehicle

Timing measurements such as jitter and skew in the range of picoseconds, for circuits with multigigahertz clocks or multigigabit-per-second serial communication interfaces are common. A Vernier-oscillator-based time-to-digital converter (TDC) is a circuit that allows picosecond-timing measurements by means of two tunable oscillators. In such a circuit, the oscillator jitter, tuning response, start-up transient, and frequency switching transient play an important role in the TDCs measurement time and accuracy. In this work, we discuss the design of an optimized, differential CML-based ring oscillator and its impact on a TDC design. Simulation results from the new oscillator show that the oscillator's short start-up and frequency switching transients have negligible effects on the accuracy of the TDC measurements. TDC simulation results show that, using two of these oscillators, accurate timing measurements in the range of 10 to 900 ps can be achieved with best-case accuracy of ~2 ps.

Design of a Tunable Differential Ring Oscillator With Short Start-Up and Switching Transients

In this paper, we present an experimental study of access impedance for vehicular power line communications (VPLC). This study aims to provide better understanding of the effects of the vehicle loads on the impedance of the VPLC plug-in access nodes. Also, some insights for the design of adaptive impedance matching are provided. We report impedance measurements of various loads and car battery, which combined with input impedance measurements from a specific sport car are used to calculate an equivalent access impedance of a PLC device connected in parallel. We show how the inductive nature of the loads dominates the overall access impedance making it on one hand more attractive for transmission in the high MHz range, and on the other more challenging for the implementation of impedance matching.

Roberto Rosales

Papers

Measurement study and transmission for in-vehicle power line communication

Crosstalk bounded uncorrelated jitter (BUJ) for high-speed interconnects

Channel characterization for power line communication in a hybrid electric vehicle

Design of a Tunable Differential Ring Oscillator With Short Start-Up and Switching Transients

A study on access impedance for vehicular power line communications