Yukai Chenimec · System and Technology Co-optimization (STCO)
Yukai Chen
Doctor of Philosophy
Power and Thermal Management For Future High-Performance Computing Architecture
About
54
Publications
38,873
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422
Citations
Introduction
Ph.D. thesis: Modelling and Simulation of Non-functional Properties of Cyber-Physical Systems
M.Sc. thesis: A Methodology for High-Level Characterization and Modeling of Aging Effects on Microprocessor Core
Additional affiliations
May 2022 - February 2023
IMEC
Position
- PostDoc Position
June 2018 - April 2022
Position
- PostDoc Position
Description
- Energy-efficient design for the Electrical Energy System(EES). Modeling and simulation of non-functional properties of Cyber Physical Systems (CPS), focusing on low power design, thermal aware design, and anti-aging design. Energy-efficient design for deep learning architecture and applications.
September 2015 - September 2017
Politecnico di Torino
Position
- Teaching Assistant
Description
- Teaching assistant for the M.Sc. course of Specification and simulation of digital system (02LQDOV).
Education
November 2014 - May 2018
October 2011 - October 2014
Publications
Publications (54)
![Figure 14. Test case study used in our validation [35].](profile/Yukai-Chen/publication/339279262/figure/fig4/AS:859535367471107@1581940609158/Test-case-study-used-in-our-validation-35_Q320.jpg)
Modern Cyber-Physical Electrical Energy Systems (CPEES) are characterized by wider adoption of sustainable energy sources and by an increased attention to optimization, with the goal of reducing pollution and wastes. This imposes a need for instruments supporting the design flow, to simulate and validate the behavior of system components and to app...
A well-known system-level strategy to reduce the energy consumption of microprocessors or microcontrollers is to organize the scheduling of the executed tasks so that it is aware of the main battery non-idealities. In the IoT domain, devices rely on simpler microcontrollers; workloads are less rich and, batteries are typically sized to guarantee li...
Temperature is a critical property of smart systems, due to its impact on reliability and to its inter-dependence with power consumption. Unfortunately, the current design flows evaluate thermal evolution ex-post on offline power traces. This does not allow to consider temperature as a dimension in the design loop, and it misses all the complex int...
The market of small drones has been recently increasing due to their use in many fields of application. The most popular drones are multirotors, in particular quadcopters. They are usually supplied with batteries of limited capacity, and for this reason their total flight time is also limited.As a consequence of the non linear characteristics of ba...
The range of operations of electric vehicles (EVs) is a critical aspect that may affect the user's attitude toward them. For manned EVs, range anxiety is still perceived as a major issue and recent surveys have shown that one-third of potential European users are deterred by this problem when considering the move to an EV. A similar consideration a...
Ultra-low-resolution Infrared (IR) array sensors offer a low-cost, energy-efficient, and privacy-preserving solution for people counting, with applications such as occupancy monitoring and visitor flow analysis in private and public spaces. Previous work has shown that Deep Learning (DL) can yield superior performance on this task. However, the lit...
Modern smartwatches often include photoplethysmographic (PPG) sensors to measure heartbeats or blood pressure through complex algorithms that fuse PPG data with other signals. In this work, we propose a collaborative inference approach that uses both a smartwatch and a connected smartphone to maximize the performance of heart rate (HR) tracking whi...
Ultra-low-resolution Infrared (IR) array sensors offer a low-cost, energy-efficient, and privacy-preserving solution for people counting, with applications such as occupancy monitoring. Previous work has shown that Deep Learning (DL) can yield superior performance on this task. However, the literature was missing an extensive comparative analysis o...
Neural Architecture Search (NAS) is quickly becoming the go-to approach to optimize the structure of Deep Learning (DL) models for complex tasks such as Image Classification or Object Detection. However, many other relevant applications of DL, especially at the edge, are based on time-series processing and require models with unique features, for w...
According to recent works, a coordinated delivery strategy in which terrestrial and aerial electric vehicles work together effectively improves delivery throughput and energy efficiency. However, most research on logistics and transportation focuses on delivery performance and does not care about energy efficiency, with three main limitations: 1. M...
The widespread adoption of EVs is limited by their reliance on batteries with presently low energy and power densities compared to liquid fuels and are subject to aging and performance deterioration over time. For this reason, monitoring the battery state of charge and state of health during the EV lifetime is a very relevant problem. This work pro...
![Fig. 2. Dependence of battery available capacity on load frequency [6].](profile/Yukai-Chen/publication/362449060/figure/fig2/AS:1185248347979782@1659596635985/Dependence-of-battery-available-capacity-on-load-frequency-6_Q320.jpg)
The widespread adoption of Electric Vehicles (EVs) is limited by their reliance on batteries with presently low energy and power densities compared to liquid fuels and are subject to aging and performance deterioration over time. For this reason, monitoring the battery State Of Charge (SOC) and State Of Health (SOH) during the EV lifetime is a very...
Low-resolution infrared (IR) array sensors offer a low-cost, low-power, and privacy-preserving alternative to optical cameras and smartphones/wearables for social distance monitoring in indoor spaces, permitting the recognition of basic shapes, without revealing the personal details of individuals. In this work, we demonstrate that an accurate dete...
Collaborative Inference (CI) optimizes the latency and energy consumption of deep learning inference through the inter-operation of edge and cloud devices. Albeit beneficial for other tasks, CI has never been applied to the sequence- to-sequence mapping problem at the heart of Neural Machine Translation (NMT). In this work, we address the specific...
Neural Architecture Search (NAS) is quickly becoming the go-to approach to optimize the structure of Deep Learning (DL) models for complex tasks such as Image Classification or Object Detection. However, many other relevant applications of DL, especially at the edge, are based on time-series processing and require models with unique features, for w...
Over the past decade, battery modeling using datasheets has been intensively researched due to the growing number of battery-powered devices. One of the typical non-ideal discharge behaviors of certain batteries is the partial recovery of their energy after a current pulse; this is known as recovery effect. Consequently, the battery runtime is gene...
Metal Additive Manufacturing (AM) is a pillar of the Industry 4.0, with many attractive advantages compared to traditional subtractive fabrication technologies. However, there are many quality issues that can be an obstacle for mass production. The in-situ camera-based monitoring and detection of defects, taking advantage of the layer-by-layer natu...
Recent works have shown that a coordinated delivery strategy in which a drone collaborates with a truck using it as a moving depot is quite effective in improving the performance and energy efficiency of the delivery process. As most of these works come from the research community of logistics and transportation, they are instead focused on the opt...
The smart energy system is characterized by a broader combination of various energy sources and energy storage devices with smart control management and increased attention to optimization for increasing energy efficiency. The fundamental dimension in the smart energy system design is the power assessment of the possible design architecture. This d...
The aging of rechargeable batteries, with its associated replacement costs, is one of the main issues limiting the diffusion of electric vehicles (EVs) as the future transportation infrastructure. An effective way to mitigate battery aging is to act on its charge cycles, more controllable than discharge ones, implementing so-called battery-aware ch...
Given the computational complexity of Recurrent Neural Networks (RNNs) inference, IoT, and mobile devices typically offload this task to the cloud. However, the execution time and energy consumption of RNN inference strongly depend on the length of the processed input. Therefore, considering also communication costs, it may be more convenient to pr...
One fundamental dimension in the design of an electrical energy system (EES) is the economic analysis of the possible design alternatives, in order to ensure not just the maximization of the energy output but also the return on the investment and the possible profits. Since the energy output and the economic figures of merit are intertwined, for an...
The energy-optimal routing of Electric Vehicles (EVs) in the context of parcel delivery is more complicated than for conventional Internal Combustion Engine (ICE) vehicles, in which the total travel distance is the most critical metric. The total energy consumption of EV delivery strongly depends on the order of delivery because of transported parc...
![Figure 4. Datasheet information for the Peimar SG280P PV module [12].](profile/Yukai-Chen/publication/342184952/figure/fig1/AS:903492025729024@1592420693639/Datasheet-information-for-the-Peimar-SG280P-PV-module-12_Q320.jpg)
Semi-empirical models of photovoltaic (PV) modules based only on datasheet information are popular in electrical energy systems (EES) simulation because they can be built without measurements and allow quick exploration of alternative devices. One key limitation of these models, however, is the fact that they cannot model the presence of bypass dio...
Finding the cost-optimal battery size in the context of parcel delivery with Electric Vehicles(EVs) requires solving a tradeoff between using the largest possible battery (so as to maximize thenumber of deliveries over a given time) and the relative costs (initial investment plus the unnecessaryincrease of the truck weight during delivery). In this...
![Fig. 3. Execution time versus input length for the CoVe network [16]....](profile/Yukai-Chen/publication/338794407/figure/fig1/AS:956323483111428@1605016694912/Execution-time-versus-input-length-for-the-CoVe-network-16-Points-and-colored-areas_Q320.jpg)
![Figure 2. Datasheet graphs for Mitsubishi's PV-MF165EB3 PV module [12].](profile/Yukai-Chen/publication/338796315/figure/fig2/AS:851535248519173@1580033232794/Datasheet-graphs-for-Mitsubishis-PV-MF165EB3-PV-module-12_Q320.jpg)
![Figure 2. Circuit-equivalent model for battery cell [24].](profile/Yukai-Chen/publication/335272651/figure/fig2/AS:793960599539713@1566306366454/Circuit-equivalent-model-for-battery-cell-24_Q320.jpg)
![Figure 3. An example route on Google Maps [26] and its related altitude...](profile/Yukai-Chen/publication/335272651/figure/fig3/AS:793960599547904@1566306366471/An-example-route-on-Google-Maps-26-and-its-related-altitude-data_Q320.jpg)
The driving range of battery electric vehicles (BEVs) has been fairly extended during recent years, as a consequence of little improvements in the energy density of lithium-based batteries. Nonetheless, charging stations are not widespread installed in all geographical areas. For these reasons, range anxiety still acts as a barrier when considering...
Driving range is one of the most critical issues for electric vehicles (EV): running out of battery charge while driving results in serious inconvenience even comparable to vehicle breakdown, as an effect of long fuel recharging times and lack of charging facilities. This may discourage EVs for current and potential customers. As an effect, the dim...
Electric vehicles (EV) are rapidly invading the market, since they are clean, quiet and energy efficient. However, there are many factors that discourage EVs for current and potential customers. Among them, driving range is one of the most critical issues: running out of battery charge while driving results in serious inconvenience even comparable...
Drones are becoming increasingly popular in the commercial market for various package delivery services. In this scenario, the mostly adopted drones are quad-rotors (i.e., quadcopters). The energy consumed by a drone may become an issue, since it may affect (i) the delivery deadline (quality of service), (ii) the number of packages that can be deli...
Lifetime maximization is a key challenge in battery-powered multi-sensor devices. Battery-aware power management strategies combine task scheduling with dynamic voltage scaling (DVS), accounting for the fact that the power drawn by the device is different from that provided by the battery due to its many non-idealities. However, state-of-the-art te...
The scheduling of at-home charging of plug-in electric vehicles (PEVs) normally depends solely on the electricity cost. However, since each charge cycle causes a small degradation of the available capacity of the battery, there is a hidden cost that typically exceeds that of the electricity. This work presents a method for minimizing the total cost...
Despite the wide body of literature on the sizing of
energy storage devices available in the domain of electrical energy
systems, the problem has not drawn much attention in the area
of battery-powered electronic systems.
It is well-known that the straightforward method of sizing
battery as the product of an expected duration and the average
load c...
In deeply scaled CMOS technologies, device aging causes transistor performance parameters to degrade over time. While reliable models to accurately assess these degradations are available for devices and circuits, the extension to these models for estimating the aging of microprocessor cores is not trivial and there is no well accepted model in the...
The high degree of heterogeneity typical of smart systems has a heavy impact on their design: the challenges are not in fact restricted to their functionality, but are also related to a number of extra-functional properties, including power consumption, temperature and aging. Current simulation- or model-based design approaches do not target a smar...
The Ragone chart is a pictorial representation to express the well-known the trade-off between available energy vs. power of different classes of energy storage devices (ESDs) like batteries or supercapacitors. Ragone charts, however, do not normally provide information about individual devices, which is an essential requirement for the actual desi...
The reduction of usable capacity of rechargeable batteries can be mitigated during the charge process by acting on some stress factors, namely, the average state-of-charge (SOC) and the charge current. Larger values of these quantities cause an increased degradation of battery capacity, so it would be desirable to keep both as low as possible, whic...
Models of power sources are essential elements in the simulation
of systems that generate, store and manage energy. In spite of the
huge difference in power scale (from the µW/mW scale of on-chip
scavengers to the MW scale of large wind turbines), they perform
a common function: converting a primary environmental quantity
into power. This paper pro...
Out of the many options available for thermal simulation of digital electronic systems, those based on solving an RC equivalent circuit of the thermal network are the most popular choice in the EDA community, as they provide a reasonable tradeoff between accuracy and complexity. HotSpot, in particular, has become the de-facto standard in these comm...
In deeply scaled CMOS technologies, device aging causes cores performance parameters to degrade over time. While accurate models to efficiently assess these degradation exist for devices and circuits, no reliable model for processor cores has gained strong acceptance in the literature. In this work, we propose a methodology for deriving an NBTI agi...
Questions
Questions (3)
In theory, we knew if two current loads have same average current value but different frequency, the discharge time of battery or the discharge SOC profile should be different; the higher frequency current load can reduce the discharge time because it reduces the nominal capacity of battery. However, except measurement, is there any existing battery model can show such difference? Dualfoil battery model seems cannot reflect such difference...
How to decide which execution-related performance counters have a high correlation with aging effects?
I want to determine the most typical event counters (pipeline stalls, cache miss, number of executed times, for example) that are provided by general processor in the market. This is a survey, please add your idea about the event counters which must be generic.
