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Open Access Publications from the University of California

Scholarly Works (11 results)

  • Article
  • Peer Reviewed
UCLA Previously Published Works (2005)

In this paper, we study an extended global routing problem with RLC crosstalk constraints. Considering simultaneous shield insertion and net ordering, we propose a multiphase algorithm to synthesize a global routing solution with track assignment to satisfy the RLC crosstalk constraint at each sink. The key algorithm phase is global routing synthesis with shield reservation and minimization based on prerouting shield estimation. Experiments using large industrial benchmarks show that compared to the best alternative with postrouting shield insertion and net ordering, the proposed algorithm with shield reservation and minimization reduces the congestion by 18.4 % with a smaller runtime. To the best of our knowledge, this is the first in-depth study on global routing synthesis with RLC crosstalk constraints.

    Cover page: Extended global routing with RLC crosstalk constraints
    • Article
    • Peer Reviewed
    UCLA Previously Published Works (2004)

    Existing layout-optimization methods for both capacitive and inductive (RLC) crosstalk reduction assume a set of interconnects with a priori given crosstalk bounds in a routing region. RLC crosstalk budgeting is critical for effectively applying these methods at the full-chip level. In this paper, we formulate a full-chip routing optimization problem with RLC crosstalk budgeting, and solve this problem with a multiphase algorithm. In phase I, we solve an optimal RLC crosstalk budgeting based on linear programming to partition crosstalk bounds at sinks into bounds for net segments in routing regions. In phase II, we perform simultaneous shield insertion and net ordering to meet the partitioned crosstalk bounds in each region. In phase III, we carry out a local refinement procedure to reduce the total number of shields. Compared with the best alternative approach in experiments, the proposed algorithm reduces the total routing area by up to 5.71% and uses less runtime. To the best of our knowledge, this work is the first in-depth study on full-chip routing optimization with RLC crosstalk budgeting.

      Cover page: Full-chip routing optimization with RLC crosstalk budgeting
      • Article
      • Peer Reviewed
      UC Berkeley Previously Published Works (2017)
        Cover page: Tracking the sources of volatile organic compounds in an occupied home
        • Article
        • Peer Reviewed
        UC Berkeley Previously Published Works (2018)
        Building ventilation rates and indoor airflow conditions influence occupants' exposure to indoor air pollutants. By making time- and space-resolved measurement of 3 inert tracers steadily released in a single-family house in California for 8 weeks in summer and 5 weeks in winter, this study quantifies the air change rate of the living zone with 2-hour time resolution; estimates airflow rates between the living zone, attic, and crawlspace; and characterizes mixing of air in the split-level living space. Occupant behaviors altered the air change rates, primarily through opening windows and secondarily through operating the heating system. The air change rate correlated with the number of window openings, accounting for 57% of the variability measured across 2 seasons. There were substantial upward interzonal airflows between the crawlspace, living zone, and attic; downward airflows were negligible by comparison. More than 70% of the airflow entering the living zone in the winter and at night during summer came through the crawlspace, rather than directly from outdoors. The airflow from the living zone to the attic increased with the attic-outdoor temperature difference, indicating that buoyancy associated with solar heating of the attic induced airflow from the living zone, increasing the air change rate.
          Cover page: Detailed investigation of ventilation rates and airflow patterns in a northern California residence.
          • Article
          • Peer Reviewed
          UC Berkeley Previously Published Works (2018)
          Residences represent an important site for bioaerosol exposure. We studied bioaerosol concentrations, emissions, and exposures in a single-family residence in northern California with 2 occupants using real-time instrumentation during 2 monitoring campaigns (8 weeks during August-October 2016 and 5 weeks during January-March 2017). Time- and size-resolved fluorescent biological aerosol particles (FBAP) and total airborne particles were measured in real time in the kitchen using an ultraviolet aerodynamic particle sizer (UVAPS). Time-resolved occupancy status, household activity data, air-change rates, and spatial distribution of size-resolved particles were also determined throughout the house. Occupant activities strongly influenced indoor FBAP levels. Indoor FBAP concentrations were an order of magnitude higher when the house was occupied than when the house was vacant. Applying an integral material-balance approach, geometric mean of total FBAP emissions from human activities observed to perturb indoor levels were in the range of 10-50 million particles per event. During the summer and winter campaigns, occupants spent an average of 10 and 8.5 hours per day, respectively, awake and at home. During these hours, the geometric mean daily-averaged FBAP exposure concentration (1-10 μm diameter) was similar for each subject at 40 particles/L for summer and 29 particles/L for winter.
            Cover page: Fluorescent biological aerosol particles: Concentrations, emissions, and exposures in a northern California residence
            • Article
            • Peer Reviewed
            UC Berkeley Previously Published Works (2017)
              Cover page: Spatially and temporally resolved measurements of volatile organic compounds in a residence
              • Article
              • Peer Reviewed
              UC Berkeley Previously Published Works (2018)
              The present study provides detailed investigation of source characteristics and emission dynamics of volatile organic compounds (VOCs) in a single-family house in California, utilizing time- and space-resolved VOC measurements for eight weeks in summer and five in winter. In total, about 300 VOCs were measured. Spatially resolved VOC measurements, in conjunction with airflow investigation using multi-tracer technique, reveal that VOCs in the living space were mainly emitted directly into the living space, with minor contributions from coupled interior spaces (crawlspace and attic) and from outdoors. Time series of most indoor VOCs were characterized by elevated baseline levels with episodic enhancements. The high baseline level highlights the importance of continuous emissions into the house from building materials and contents. Associated emissions rates were quantified with 2-h resolution. Influences of environmental parameters on emissions were explored. Episodic enhancements were associated with occupants and their activities, such as cooking and personal-care-product use.
                Cover page: Spatially and temporally resolved emissions of volatile organic compounds in a residence
                • Article
                • Peer Reviewed
                UC Berkeley Previously Published Works (2018)
                Occupant associated emissions of volatile organic compounds (VOCs) can materially influence indoor air quality (IAQ). Knowledge of emission factors can contribute to improved exposure and risk assessments and also can aid in designing effective control measures to improve IAQ. The advent of instruments capable of sensitive, speciated VOC measurements with high time resolution allows for characterizing occupant-associated VOC emissions from observational monitoring studies conducted in real buildings under normal occupancy. This presentation highlights VOC emissions associated with residential activities, such as cooking and cleaning.
                  Cover page: Interpreting time-resolved residential monitoring data to characterize emissions of volatile organic compounds from occupant activities
                  • Article
                  • Peer Reviewed
                  UC Berkeley Previously Published Works (2018)
                  Human-emitted volatile organic compounds and other trace gases often dominate concentrations of occupied indoor atmospheres. With the application of real-time mass spectrometry, it has become possible to measure time-resolved behaviour of breath metabolites, skin emanations including oil oxidation products and microbial VOCs, and other bioeffluents. The temporal and mass spectral resolution enables deeper understanding of their impact on air quality, VOC exposure, and sensory perceptions. Per-person CO2 and VOC emissions derived from similar groups of students indicate consistencies in major breath metabolites. Skin-emitted VOCs can be differentiated from volatilization of consumer care products by their distinctive diurnal patterns. Here we synthesize recent approaches to time-resolved measurements of human bioeffluents by PTRMS to inspire new research directions in indoor air science.
                    Cover page: Field measurements of human VOC bioeffluents using PTRMS
                    • Article
                    • Peer Reviewed
                    UC Berkeley Previously Published Works (2018)
                    Knowledge of human exposures to volatile organic compounds (VOCs) is critical for understanding their impact on human health. We measured time-resolved concentrations in combination with collecting occupancy data for a wide range of VOCs in two residences in northern California. We report exposures to hundreds of volatile organic compounds present indoors, spanning orders of magnitude in abundance, toxicity and reactivity. We show that concentrations of most VOCs were considerably higher indoors than outdoors, with the sum of measured VOCs being of an order of magnitude higher, in each season and each residence. Occupant's activities were the largest source of short-term episodic exposures, while VOCs from wood degradation were prominent contributors to chronic exposures. We show a comprehensive account of known and newly observed air toxics, their sources, and quantify time-resolved and daily-integrated exposures. We found that daily-integrated measurements could underestimate total exposure to VOCs and point to the need for time-resolved concentration measurements to accurately assess exposures.
                      Cover page: Time-resolved exposure to volatile organic compounds in two California residences
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