Tiansong Cui

Bio: Tiansong Cui is an academic researcher from University of Southern California. The author has contributed to research in topics: Smart grid & CMOS. The author has an hindex of 10, co-authored 23 publications receiving 273 citations.

Dynamic thermal management for FinFET-based circuits exploiting the temperature effect inversion phenomenon

Abstract: Due to limits on the availability of the energy source in many mobile user platforms (ranging from handheld devices to portable electronics to deeply embedded devices) and concerns about how much heat can effectively be removed from chips, minimizing the power consumption has become a primary driver for system-on-chip designers. Because of their superb characteristics, FinFETs have emerged as a promising replacement for planar CMOS devices in sub-20nm CMOS technology nodes. However, based on extensive simulations, we have observed that the delay vs. temperature characteristics of FinFET-based circuits are fundamentally different from that of the conventional bulk CMOS circuits, i.e., the delay of a FinFET circuit decreases with increasing temperature even in the super-threshold supply voltage regime. Unfortunately, the leakage power dissipation of the FinFET-based circuits increases exponentially with the temperature. These two trends give rise to a tradeoff between delay and leakage power as a function of the chip temperature, and hence, lead to the definition of an optimum chip temperature operating point (i.e., one that balances concerns about the circuit speed and power efficiency.) This paper presents the results of our investigations into the aforesaid temperature effect inversion (TEI) and proposes a novel dynamic thermal management (DTM) algorithm, which exploits this phenomenon to minimize the energy consumption of FinFET-based circuits without any appreciable performance penalty. Experimental results demonstrate 40% energy saving (with no performance penalty) can be achieved by the proposed TEI-aware DTM approach compared to the best-in-class DTMs that are unaware of this phenomenon.

Concurrent optimization of consumer's electrical energy bill and producer's power generation cost under a dynamic pricing model

Abstract: Demand response is a key element of the smart grid technologies. This is a particularly interesting problem with the use of dynamic energy pricing schemes which incentivize electricity consumers to consume electricity more prudently in order to minimize their electric bill. On the other hand optimizing the number and production time of power generation facilities is a key challenge. In this paper, three models are presented for consumers, utility companies, and a third-part arbiter to optimize the cost to the parties individually and in combination. Our models have high quality and exhibit superior performance, by realistic consideration of non-cooperative energy buyers and sellers and getting real-time feedback from their interactions. Simulation results show that the energy consumption distribution becomes very stable during the day utilizing our models, while consumers and utility companies pay lower cost.

An electricity trade model for microgrid communities in smart grid

Abstract: Distributed microgrid network is the major trend of future smart grid, which contains various kinds of renewable power generation centers and a small group of energy users. In the distributed power system, each microgrid acts as a “prosumer” (producer and consumer) and maximizes its own social welfare. In addition, different microgrids can interact among each other through trading over a marketplace. In this paper, two models are introduced for microgrids to deal with the welfare maximization problems. In the first model, a microgrid is considered as a closed economy group and decides the optimal power generation distribution in terms of time. In the second model, each microgrid can trade with its neighborhoods and thus achieve a welfare increase from making use of its comparative advantage on power generation during a certain period of time. For each model, an efficient solution is presented. Experimental result shows the accuracy and efficiency of our presented solutions.

7nm FinFET standard cell layout characterization and power density prediction in near- and super-threshold voltage regimes

Abstract: In this paper, we present a power density analysis for 7nm FinFET technology node, including both near-threshold and super-threshold operations. We first build a Liberty-formatted standard cell library by selecting the appropriate number of fins for the pull-up and pull-down networks of each logic cell. The layout of each cell then is characterized based on the lambda-based layout design rules for FinFET devices. Finally, the power density of the 7nm FinFET technology node is analyzed and compared with the state-of-the-art 45nm CMOS technology node for different circuits. Hspice results show that the power density of each 7nm FinFET circuit is at least 10 to 20 times larger than that of the same 45nm CMOS circuit in near- and super-threshold voltage regimes. Also the power densities of FinFET circuits are shown to be much higher than the limit of air cooling, which necessitates careful thermal management for the FinFET technology.

Optimal control of PEVs for energy cost minimization and frequency regulation in the smart grid accounting for battery state-of-health degradation

Abstract: Plug-in electric vehicles (PEVs) are considered the key to reducing the fossil fuel consumption and an important part of the smart grid. The plug-in electric vehicle-to-grid (V2G) technology in the smart grid infrastructure enables energy flow from PEV batteries to the power grid so that the grid stability is enhanced and the peak power demand is shaped. PEV owners will also benefit from V2G technology as they will be able to reduce energy cost through proper PEV charging and discharging scheduling. Moreover, power regulation service (RS) reserves have been playing an increasingly important role in modern power markets. It has been shown that by providing RS reserves, the power grid achieves a better match between energy supply and demand in presence of volatile and intermittent renewable energy generation. This paper addresses the problem of PEV charging under dynamic energy pricing, properly taking into account the degradation of battery state-of-health (SoH) during V2G operations as well as RS provisioning. An overall optimization throughout the whole parking period is proposed for the PEV and an adaptive control framework is presented to dynamically update the optimal charging/discharging decision at each time slot to mitigate the effect of RS tracking error. Experimental results show that the proposed optimal PEV charging algorithm minimizes the combination of electricity cost and battery aging cost in the RS provisioning power market.

A Survey on Demand Response Programs in Smart Grids: Pricing Methods and Optimization Algorithms

Abstract: The smart grid concept continues to evolve and various methods have been developed to enhance the energy efficiency of the electricity infrastructure. Demand Response (DR) is considered as the most cost-effective and reliable solution for the smoothing of the demand curve, when the system is under stress. DR refers to a procedure that is applied to motivate changes in the customers' power consumption habits, in response to incentives regarding the electricity prices. In this paper, we provide a comprehensive review of various DR schemes and programs, based on the motivations offered to the consumers to participate in the program. We classify the proposed DR schemes according to their control mechanism, to the motivations offered to reduce the power consumption and to the DR decision variable. We also present various optimization models for the optimal control of the DR strategies that have been proposed so far. These models are also categorized, based on the target of the optimization procedure. The key aspects that should be considered in the optimization problem are the system's constraints and the computational complexity of the applied optimization algorithm.

Parallel CAD: Algorithm Design and Programming Special Section Call for Papers TODAES: ACM Transactions on Design Automation of Electronic Systems

Abstract: High-performance parallel computer architecture and systems have been improved at a phenomenal rate. In the meantime, VLSI computer-aided design (CAD) software for multibillion-transistor IC design has become increasingly complex and requires prohibitively high computational resources. Recent studies have shown that, numerous CAD problems, with their high computational complexity, can greatly benefit from the fast-increasing parallel computation capabilities. However, parallel programming imposes big challenges for CAD applications. Fully exploiting the computational power of emerging general-purpose and domain-specific multicore/many-core processor systems, calls for fundamental research and engineering practice across every stage of parallel CAD design, from algorithm exploration, programming models, design-time and run-time environment, to CAD applications, such as verification, optimization, and simulation. This journal special section will cover recent progress on parallel CAD research, including algorithm foundations, programming models, parallel architectural-specific optimization, and verification. More specifically, papers with in-depth and extensive coverage of the following topics will be considered, as well as other topics relevant to the design of parallel CAD algorithms and software tools. 1. Parallel algorithm design and specification for CAD applications 2. Parallel programming models and languages of particular use in CAD 3. Runtime support and performance optimization for CAD applications 4. Parallel architecture-specific design and optimization for CAD applications 5. Parallel program debugging and verification techniques particularly relevant for CAD The papers should be submitted via the Manuscript Central website and should adhere to standard ACM TODAES formatting requirements (http://todaes.acm.org/). The page count limit is 25.

International Economics: Theory and Policy

Abstract: International Economics: Theory and Policy is built on Steve Suranovic’s belief that students need to learn the theory and models to understand how economics works and how economists understand the world And, that these ideas are accessible to most students if they are explained thoroughlySo, if you are looking for an International Economics text that will prepare your PhD students while promoting serious comprehension for the non-economics major, Steve Suranovic’s International Economics: Theory and Policy is for you International Economics: Theory and Policy presents numerous models in some detail; not by employing advanced mathematics, but rather by walking students through a detailed description of how a model’s assumptions influence its conclusions Then, students learn how the models connect with the real world Steve’s book covers positive economics to help answer the normative questions; for example, what should a country do about trade policy, or about exchange rate policy? The results from models give students insights that help us answer these questions Thus, this text strives to explain why each model is interesting by connecting its results to some aspect of a current policy issue This text eliminates some needlessly difficult material while adding and elaborating on other principles For example, the development of the relative supply/demand structure, or the presentation of offer curves, are omitted as to not go too deeply into topics that tend to confuse many students at this level Steve developed new approaches in this text including a simple way to present the Jones’ magnification effects, a systematic method to teach the theory of the second best, and a unique description of valid reasons to worry about trade deficits These new approaches help students learn the concepts and models and derive conclusions from them If you like to take a comprehensive look at trade policies, be sure to check out the chapter on Trade Policy (7) It provides a comprehensive look at many more trade policies than are found in many of the printed textbooks on the market todayInternational Economics: Theory and Policy by Steve Suranovic is intended for use in a full semester trade course, a full semester finance course, or a one semester trade/finance course

Energy Cooperation Optimization in Microgrids With Renewable Energy Integration

Abstract: Microgrids are key components of future smart grids, which integrate distributed renewable energy generators to efficiently serve the load locally. However, the intermittent nature of renewable energy generations hinders the reliable operation of microgrids. Besides the commonly adopted methods such as deploying energy storage system (ESS) and supplementary fuel generator to address the intermittency issue, energy cooperation among microgrids by enabling their energy exchange for sharing is an appealing new solution. In this paper, we consider the energy management problem for two cooperative microgrids each with individual renewable energy generator and ESS. First, by assuming that the microgrids’ renewable energy generation/load amounts are perfectly known ahead of time, we solve the off-line energy management problem optimally. Based on the obtained solution, we study the impacts of microgrids’ energy cooperation and their ESSs on the total energy cost. Next, inspired by the off-line optimization solution, we propose online algorithms for the real-time energy management of the two cooperative microgrids. It is shown via simulations that the proposed online algorithms perform well in practice, have low complexity, and are also valid under arbitrary realizations of renewable energy generations/loads. Finally, we present one method to extend our proposed online algorithms to the general case of more than two microgrids based on a clustering approach.

A review of strategies for building energy management system: Model predictive control, demand side management, optimization, and fault detect & diagnosis

Abstract: Building energy use is expected to grow by more than 40% in the next 20 years. Electricity remains the largest energy source consumed by buildings, and that demand is growing. To mitigate the impact of the growing demand, strategies are needed to improve buildings' energy efficiency. In residential buildings home appliances, water, and space heating are answerable for the increase of energy use, while space heating and other miscellaneous equipment are behind the increase of energy utilization in non-residential buildings. Building energy management systems support building managers and proprietors to increase energy efficiency in modern and existing buildings, non-residential and residential buildings can benefit from building energy management system to decrease energy use. Base on the type of building, different management strategies can be used to achieve energy savings. This paper presents a review of management strategies for building energy management systems for improving energy efficiency. Different management strategies are investigated in non-residential and residential buildings. Following this, the reviewed researches are discussed in terms of the type of buildings, building systems, and management strategies. Lastly, the paper discusses future challenges for the increase of energy efficiency in building energy management system.