arXiv subjects

Ning Zeng

Publications and source records attributed to Ning Zeng.

4 recordsLinked to original sources

arXiv2026

NMKFR: A Robust Framework for Time-Aware Cold-Start Recommendation

Item cold-start recommendation is difficult when new items have sparse early interactions and appear in recommendation environments that keep changing over time. Static content, early feedback, and temporal-state evidence are all useful, but their reliability varies across the item lifecycle. This work proposes a framework--Neural Memory Kalman Fusion Recommender (NMKFR), which combines a Titans-based semantic encoder with time-aware Kalman state tracking. The semantic branch extracts memory-enhanced item observations from text, while the temporal branch estimates latent states under irregular interaction intervals. The NMKFR further uses posterior covariance as an uncertainty signal to calibrate semantic memory retrieval and adaptive static-temporal fusion. Experiments on Amazon Video Games and MovieLens-32M evaluate NMKFR under time-aware and item cold-start protocols using sampled candidate ranking. Across the reported comparisons, ablations, diagnostics, and robustness analyses, NMKFR achieves the strongest retained results and exhibits bounded uncertainty-related internal behavior. These findings provide empirical evidence for posterior-covariance-guided semantic-temporal fusion under the evaluated offline settings.

cs.IR↗

arXiv2023

Implementation Guidance for Wood Harvesting and Storage

This implementation guidance focuses on carbon removal and sequestration via wood harvesting and storage (WHS), a process where woody biomass, with the embedded carbon, is stored for long timescales in shallow geologic storage. The engineering structure designed to ensure such durable storage by preventing biomass decomposition is called a Wood Vault. This guidance contains the requirements for a basic Wood Vault project, and is intended to aid project developers, verifiers, and registries in this space. It describes a set of requirements that govern the end-to-end process of carbon removal and sequestration. This includes carbon accounting, wood sourcing via wood residual (WR) utilization, Wood Vault construction and maintenance, as well as processes for monitoring, verification, and credit issuance. Carbon accounting requirements include baseline, or counterfactual specification, and full life cycle analysis (LCA) within a specified process boundary. For the vault itself, the guidance describes a buried vault with the burial chamber covered by a layer of low permeability material to create anoxic condition. Other types of vaults can also be used to adjust to local environmental, transport, and economic constraints. Monitoring and verification requirements include in-situ sensors, gas sampling, sample excavations, and site maintenance. This guidance also contemplates land ownership and legal assurances, as well as environmental and societal impact assessments. The implementation guidance concludes with recommendations regarding auditing, certification and carbon credit issuance.

physics.soc-ph↗

arXiv2021

Decreasing emissions and increasing sink capacity to support China in achieving carbon neutrality before 2060

In September 2020, President Xi Jinping announced that China strives to achieve carbon neutrality before 2060. This ambitious and bold commitment was well received by the global community. However, the technology and pathway are not so clear. Here, we conducted an extensive review covering more than 200 published papers and summarized the key technologies to achieve carbon neutrality. We projected sectoral CO2 emissions for 2020-2050 based on our previous studies and published scenarios. We applied a medium sink scenario for terrestrial sinks due to the potential resource competition and included an ocean sink, which has generally not been included in previous estimates. We analyzed and revisited China's historical terrestrial carbon sink capacity from 1980-2020 based on multiple models and a literature review. To achieve neutrality, it is necessary to increase sink capacity and decrease emissions from many sources. On the one hand, critical measures to reduce emissions include decreasing the use of fossil fuels; substantially increasing the proportion of the renewable energy and nuclear energy. On the other hand, the capacity of future carbon sinks is projected to decrease due to the natural evolution of terrestrial ecosystems, and anthropogenic management practices are needed to increase sink capacity, including increasing the forest sinks through national ecological restoration projects and large-scale land greening campaigns; increasing wood harvesting and storage; and developing CCUS. This paper provides basic source and sink data,and established and promising new technologies for decreasing emissions and increasing sinks for use by the scientific community and policy makers.

physics.ao-ph↗

arXiv2020

Global to local impacts on atmospheric CO2 caused by COVID-19 lockdown

The world-wide lockdown in response to the COVID-19 pandemic in year 2020 led to economic slowdown and large reduction of fossil fuel CO2 emissions, but it is unclear how much it would reduce atmospheric CO2 concentration, and whether it can be observed. We estimated that a 7.9% reduction in emissions for 4 months would result in a 0.25 ppm decrease in the Northern Hemisphere CO2, an increment that is within the capability of current CO2 analyzers, but is a few times smaller than natural CO2 variabilities caused by weather and the biosphere such as El Nino. We used a state-of-the-art atmospheric transport model to simulate CO2, driven by a new daily fossil fuel emissions dataset and hourly biospheric fluxes from a carbon cycle model forced with observed climate variability. Our results show a 0.13 ppm decrease in atmospheric column CO2 anomaly averaged over 50S-50N for the period February-April 2020 relative to a 10-year climatology. A similar decrease was observed by the carbon satellite GOSAT3. Using model sensitivity experiments, we further found that COVID, the biosphere and weather contributed 54%, 23%, and 23% respectively. This seemingly small change stands out as the largest sub-annual anomaly in the last 10 years. Measurements from global ground stations were analyzed. At city scale, on-road CO2 enhancement measured in Beijing shows reduction of 20-30 ppm, consistent with drastically reduced traffic during the lockdown. The ability of our current carbon monitoring systems in detecting the small and short-lasting COVID signal on the background of fossil fuel CO2 accumulated over the last two centuries is encouraging. The COVID-19 pandemic is an unintended experiment whose impact suggests that to keep atmospheric CO2 at a climate-safe level will require sustained effort of similar magnitude and improved accuracy and expanded spatiotemporal coverage of our monitoring systems.

physics.ao-ph↗