Hasil untuk "Municipal refuse. Solid wastes"

Yuxiao Lu, Lin Xu, Yang Sun et al.

Large language models (LLMs) aligned for safety often suffer from over-refusal, the tendency to reject seemingly toxic or benign prompts by misclassifying them as toxic. This behavior undermines models' helpfulness and restricts usability in sensitive or nuanced contexts. While prior work has proposed mitigation strategies such as data augmentation and activation steering, these approaches often face a trade-off: reducing over-refusal typically degrades the model's ability to reject genuinely harmful content. We argue that this issue arises from the ambiguous influence of toxic and seemingly toxic prompts on the model's learning dynamics. To address it, we introduce a preceding alignment stage, DCR: Discernment via Contrastive Refinement. Both theoretically and empirically, we demonstrate that contrastive refinement improves an LLM's capacity to distinguish truly toxic prompts from superficially toxic ones. Evaluation across diverse benchmarks shows that our method effectively reduces over-refusal while preserving the safety benefits of alignment. Importantly, it achieves this with minimal degradation of general capabilities, offering a more principled and robust direction for safety alignment.

Meizhen Huang, Zefei Wu, Chenxuan Lou et al.

We studied double-layer WSe2 stacked on opposite sides of thin layers of hexagonal Boron nitride with different densities of electrons and holes. For a fixed hole density, the Coulomb drag resistance is found to exhibit plateaus approximately equal to $-h/(4e^2)$ and $-h/(2e^2)$ as the electron density is changed. When the number of electrons is equal to the number of holes, an exciton solid forms whose transport of quantum edge defects gives rise to the drag resistance. When the electron and hole densities are different, the excess electrons form a solid embedded in the exciton solid. The Coulomb drag resistance of the exciton solid comes from the one-dimensional transport of the two lowest energy channels of quantum edge vacancy-interstitial pairs. This corresponds to the first plateau. With the embedded solid, one of these channels is blocked. This corresponds to the second plateau. Transport experiments in the Corbino geometry with no edges and extra heavier holes were carried out. The plateaus disappeared. Three peaks in the resistance at different hole densities were observed. We interpret that the three peaks correspond to the commensurate exciton and two classes of hole solids. We performed phonon calculations of these states and found that the stability of these exciton-based quantum solids shows good agreement with experiment. Our results establish classes of extreme quantum solid states, opening additional avenues for the study of strongly correlated quantum transport phenomena involving quantum defect states.

Vishnu Kabir Chhabra, Mohammad Mahdi Khalili

The rapid growth of large language models has spurred significant interest in model compression as a means to enhance their accessibility and practicality. While extensive research has explored model compression through the lens of safety, findings suggest that safety-aligned models often lose elements of trustworthiness post-compression. Simultaneously, the field of mechanistic interpretability has gained traction, with notable discoveries, such as the identification of a single direction in the residual stream mediating refusal behaviors across diverse model architectures. In this work, we investigate the safety of compressed models by examining the mechanisms of refusal, adopting a novel interpretability-driven perspective to evaluate model safety. Furthermore, leveraging insights from our interpretability analysis, we propose a lightweight, computationally efficient method to enhance the safety of compressed models without compromising their performance or utility.

Andrea Spinelli, Francesca Maggioni, Tânia Rodrigues Pereira Ramos et al.

In this paper we present a multi-stage stochastic optimization model to solve an inventory routing problem for recyclable waste collection. The objective is the maximization of the total expected profit of the waste collection company. The decisions are related to the selection of the bins to be visited and the corresponding routing plan in a predefined time horizon. Stochasticity in waste accumulation is modeled through scenario trees generated via conditional density estimation and dynamic stochastic approximation techniques. The proposed formulation is solved through a rolling horizon approach, providing a worst-case analysis on its performance. Extensive computational experiments are carried out on small- and large-sized instances based on real data provided by a large Portuguese waste collection company. The impact of stochasticity on waste generation is examined through stochastic measures, and the performance of the rolling horizon approach is evaluated. Some managerial insights on different configurations of the instances are finally discussed.

E. Bilokopytov, J. Conradie, V. G. Troitsky et al.

While there is a well developed theory of locally solid topologies, many important convergences in vector lattice theory are not topological. Yet they share many properties with locally solid topologies. Building upon the theory of convergence structures, we develop a theory of locally solid convergences, which generalize locally solid topologies but also includes many important non-topological convergences on a vector lattice. We consider some natural modifications of such structures: unbounded, bounded, and Choquet. We also study some specific convergences in vector lattices from the perspective of locally solid convergence structures.

Jiacheng Tang

Solid abelian groups, as introduced by Dustin Clausen and Peter Scholze, form a subcategory of all condensed abelian groups satisfying some ''completeness'' conditions and having favourable categorical properties. Given a profinite ring $R$, there is an associated condensed ring $\underline{R}$ which is solid. We show that the natural embedding of profinite $R$-modules into solid $\underline{R}$-modules preserves $\mathrm{Ext}$ and tensor products, as well as the fact that profinite rings are analytic.

Raiyan Rahman, Mohsena Chowdhury, Yueyang Tang et al.

The escalating global concern over extensive food wastage necessitates innovative solutions to foster a net-zero lifestyle and reduce emissions. The LILA home composter presents a convenient means of recycling kitchen scraps and daily food waste into nutrient-rich, high-quality compost. To capture the nutritional information of the produced compost, we have created and annotated a large high-resolution image dataset of kitchen food waste with segmentation masks of 19 nutrition-rich categories. Leveraging this dataset, we benchmarked four state-of-the-art semantic segmentation models on food waste segmentation, contributing to the assessment of compost quality of Nitrogen, Phosphorus, or Potassium. The experiments demonstrate promising results of using segmentation models to discern food waste produced in our daily lives. Based on the experiments, SegFormer, utilizing MIT-B5 backbone, yields the best performance with a mean Intersection over Union (mIoU) of 67.09. Class-based results are also provided to facilitate further analysis of different food waste classes.

Eugene Bilokopytov

We carry on a more detailed investigation of the composition of locally solid convergences as introduced in [BCTvdW24], as well as the corresponding notion of idempotency considered in [Bil23]. In particular, we study the interactions between these two concepts and various operations with convergences. We prove associativity of the composition and show that the adherence of an ideal with respect to an idempotent convergence is equal to its closure. Some results from [KT18] about unbounded modification of locally solid topologies are generalized to the level of locally solid idempotent convergences. A simple application of the composition allows us to answer a question from [BCTvdW24] about minimal Hausdorff locally solid convergences. We also show that the weakest Hausdorff locally solid convergence exists on an Archimedean vector lattice if and only if it is atomic.

Mingxue Xin, Yingjie Sun, Weihua Li et al.

With the development of incineration technologies, incineration has become the most common treatment method of municipal solid waste in China. However, stabilized fly ash may enter landfills during the transition from landfill to incineration, which caused uncertain impact on landfill waste stabilization. Two simulated co-landfill columns were constructed based on different co-landfill methods (layer co-landfill and mixed co-landfill) to investigate the effect of stabilized fly ash co-landfilled municipal solid waste for bacterial community succession and change in metabolic pathways during hydrolysis-acidogenesis stage. The mixed co-landfill method resulted in higher degree of organic matter degradation, and the concentrations of volatile fatty acids (VFA) and chemical oxygen demand (COD) in leachate were higher. The dominant phyla were Firmicutes in the layered co-landfill column and Bacteroidetes in mixed co-landfill column. The dominant genera for the total bacterial composition and VFA production were different, Pseudomonas and Propionibacterium, Proteiniphilum and unclassified Bacteroides were the dominant genera responsible for VFA generation in the layered and mixed co-landfill columns. The genes for butyrate production were enriched in the layered co-landfill column, whereas those related to acetate production were enriched in mixed co-landfill column. However, the layered co-landfill inhibited the microbial metabolic activity at the end of the co-landfill process.

B. Manimekalai, S. Sivanesan, P. Kumar

“Aged refuse” corresponds to municipal solid waste material dumped in land, for several years. This solid waste material is chosen as an adsorbent for the current study since it is available abundantly in the state of Tamil Nadu, India, and has not been used for any other applications. The current study was conducted to get rid of the element chromium (VI) from wastewater by using the adsorption process. The aged refuse was analytically tested through various processes such as BET, TGA, XRD, SEM, and FTIR to determine the surface morphology, functional groups, thermal stability, nature of the crystalline, and surface area. The researchers conducted the batch adsorption study to validate the influence exerted by different sorts of adsorption parameters like contact time (10-100 min), initial concentration of the pollutant (50 mg·L-1 to 250 mg·L-1), pH (1-7), and the dosage of the adsorbent (0.5 g·L-1-3.0 g·L-1). In the current study, the researchers achieved the maximum adsorption capacity of 195.54 mg·g-1. From the kinetic results, it can be understood that the pseudo-first-order model was the most suitable kinetic model. Further, the study outcomes confirm that the Langmuir isotherm model is the best fit by isotherm studies which indicate the monolayer adsorption process. This study indicated that the aged refuse can be potentially used in removing Cr (VI) from water environment under standard optimized conditions.

M. Zeeshan, Rohan R. Pande, P. Bhale

Niful Islam, Md. Mehedi Hasan Jony, Emam Hasan et al.

Improper disposal of e-waste poses global environmental and health risks, raising serious concerns. The accurate classification of e-waste images is critical for efficient management and recycling. In this paper, we have presented a comprehensive dataset comprised of eight different classes of images of electronic devices named the E-Waste Vision Dataset. We have also presented EWasteNet, a novel two-stream approach for precise e-waste image classification based on a data-efficient image transformer (DeiT). The first stream of EWasteNet passes through a sobel operator that detects the edges while the second stream is directed through an Atrous Spatial Pyramid Pooling and attention block where multi-scale contextual information is captured. We train both of the streams simultaneously and their features are merged at the decision level. The DeiT is used as the backbone of both streams. Extensive analysis of the e-waste dataset indicates the usefulness of our method, providing 96% accuracy in e-waste classification. The proposed approach demonstrates significant usefulness in addressing the global concern of e-waste management. It facilitates efficient waste management and recycling by accurately classifying e-waste images, reducing health and safety hazards associated with improper disposal.

L. Joseph, R. Prasad

Abstract The Pacific Small Island Developing States (PSIDS) are largely reliant on fossil fuels for electricity generations and this dependency makes these Island States immensely vulnerable to global fuel price volatility since the excess outflow of money on fuel imports not only affects the economic growth but also hinders the sustainable development. Additionally, waste management in these small countries is economically and environmentally expensive and mostly dumped in open/closed-dumps and landfills which decompose and releases notorious greenhouse gases (i.e., methane and carbon dioxide, etc.). Amalgamating these two disparate issues, this study aims to find a mutual solution by exploring the feasibility of waste-to-energy (WtE) potentials via different technologies at the selected sites. Using the population and per capita waste generation data of fifteen selected sites of eight PSIDS, a waste profile of each site is evaluated. Then, the waste generation over the projected 20 years is used to determine the electricity generation potential of each site under the proposed alternative scenarios (i.e., 2 – landfill gas to energy (LFGTE) technology, 3 – mass-burn incineration, 4 – hybrid mechanical-biological treated (MBT) anaerobic digestion (AD) and LFGTE technology, and 5 – hybrid MBT-AD and refuse-derived fuel (RDF) incineration). These four scenarios (2–5) are compared to the Business-as-Usual case denoted as scenario 1. To test the economic viability, the Net Present Value, Levelized Cost of Energy, and Payback Period of each site is ascertained. Further economic benefits are assessed through the recycling of materials including plastics (under scenario 4 only), glass, and metals (under all scenarios). Emissions and energy consumption of each scenario are analysed using the Waste Reduction Model (WARM). The outcome of this study revealed that scenario 3 offers the greatest potential in terms of electricity generation, at Port Moresby (PNG1), Papua New Guinea site having the highest potential (i.e., 78.86 GWh) and Kosrae (FSM4), Federated States of Micronesia has the lowest generation potential of only 92.86 MWh. This scenario 3 (mass-burn incineration) was also supported by the economic assessment. It was also found that recycling brought in additional economic benefits and also helped offset CO2-equivalent emissions and contributed towards energy savings. Multi-level multi-criteria decision analysis (ML-MCDA) was performed to select the most viable waste management alternative based on technical, economic, environmental, and stakeholder preferences. The priorities assigned to the respective scenarios for all fifteen sites were as such: scenario 3 > scenario 5 > scenario 4 > scenario 2 > scenario 1.

K. Świechowski, Paweł Stępień, Ewa Syguła et al.

In work, data from carbonization of the eight main municipal solid waste components (carton, fabric, kitchen waste, paper, plastic, rubber, paper/aluminum/polyethylene (PAP/AL/PE) composite packaging pack, wood) carbonized at 300–500 °C for 20–60 min were used to build regression models to predict the biochar properties (proximate and ultimate analysis) for particular components. These models were then combined in general models that predict the properties of char made from mixed waste components depending on pyrolysis temperature, residence time, and share of municipal solid waste components. Next, the general models were compared with experimental data (two mixtures made from the above-mentioned components carbonized at the same conditions). The comparison showed that most of the proposed general models had a determination coefficient (R2) over 0.6, and the best prediction was found for the prediction of biochar mass yield (R2 = 0.9). All models were implemented into a spreadsheet to provide a simple tool to determine the potential of carbonization of municipal solid waste/refuse solid fuel based on a local mix of major components.

B. Zaman, B. P. Samadikun, N. Hardyanti et al.

Abstract Municipal solid waste (MSW) is an energy resource with sufficient energy/calorific value, making it a suitable substitute for fuel. This study investigated the effect of air flow rate on the MSW calorific value, the hemicellulose content, and the MSW degradation rate in a biodrying process. Four biodrying reactors equipped with flowrate and temperature recorders were used in the study. The air flow rate was varied as follows: 0 L/min/kg, 2 L/min/kg, 4 L/min/kg, and 6 L/min/kg, corresponding to reactors R1, R2, R3, and R4, respectively. The calorific value, water content, hemicellulose content, organic C content, and total N were measured on day 1, day 15, and day 30. The results showed that the biodrying process could increase the calorific value by 55.3 %, whereas the control reactor could increase the calorific value by only 4.7 %. The highest calorific value was 17.63 MJ/kg, at an air flow rate of 4 L/min/kg. The air flow rate had a significant effect on increasing the calorific value (sig.0.05). The biodrying process is the suitable method to increase the calorific value of MSW while reducing its water content; thus, the process promotes the realization of waste to energy as refuse-derived fuel.

Jun Li, Lixian Wang, Y. Chi et al.

The production of clean and efficient energy from municipal solid waste (MSW) is extremely urgent matter due to an increasing energy demand and environmental concerns. In this study, a high steam parameter (520 °C, 7.9 MPa) circulating fluidized bed (CFB) MSW incineration system, equipped with a mechanical, biological treatment and external heat exchanger systems, was introduced and a comparative study with a typical mechanical grate (450 °C, 5.3 MPa) incineration system and conventional CFB (485 °C, 5.3 MPa) incineration system was carried out from a life-cycle, environmental and exergetic perspective which could assess different energy and material outputs based on real operating data. Moreover, the potential system optimization of this advanced CFB system was proposed. The results showed that the advanced CFB system was more environmentally friendly and resource-efficient than conventional MSW incineration systems. The recovery of material should be given priority over energy recovery. According to the assessment of the environment, and energy and material recovery, a process improvement with an incinerated refuse-derived fuel and a semi-compost produced by MBT as a soil conditioner was highly recommended.

M. Shumal, Ahmad Reza Taghipour Jahromi, A. Ferdowsi et al.

Abstract Refused Derived Fuel (RDF) could be considered as an alternative energy source, which not only helps to improve waste management, but also effectively reduce energy consumption and environmental pollution in huge industries. In the present study, the potential of energy valorization of rejected streams of municipal solid waste (MSW) processed in Isfahan mechanical and biological treatment (MBT) plant is investigated through RDF production. Therefore, various physical and chemical analysis of mechanical treatment rejects (MTR) and composting rejects (CR), as two streams being currently landfilled, were carried out. The results show that, RDF produced from both of these two streams could be classified as net calorific value (NCV): 3, Cl: 1 and Hg: 1 according to the European committee for standardization (CEN standard). Considering the amount of produced RDF from these two streams in Isfahan (300 t/d from MTR and 120 t/d from CR) and their NCVs, about 2 million GJ/year would be saved. As a result, in many cities of developing countries with the same condition like Isfahan, MTR and CR can be used as sources of RDF production and alternative fuels in the cement industry.

Zsolt Regály

The solid material of protoplanetary discs forms an asymmetric pattern around a low-mass planet (M_p<=10M_Earth) due to the combined effect of dust-gas interaction and the gravitational attraction of the planet. Recently, it has been shown that although the total solid mass is negligible compared to that of gas in protoplanetary discs, a positive torque can be emerged by a certain size solid species. The torque magnitude can overcome that of gas which may result in outward planetary migration. In this study, we show that the accretion of solid species by the planet strengthens the magnitude of solid torque being either positive or negative. We run two-dimensional, high-resolution (1.5Kx3K) global hydrodynamic simulations of an embedded low-mass planet in a protoplanetary disc. The solid material is handled as a pressureless fluid. Strong accretion of well-coupled solid species by a M_p<0.3M_Earth protoplanet results in the formation of such a strongly asymmetric solid pattern close to the planet that the positive solid torque can overcome that of gas by two times. However, the accretion of solids in the pebble regime results in increased magnitude negative torque felt by protoplanets and strengthened positive torque for Earth-mass planets. For M_p>=3M_Earth planets the magnitude of the solid torque is positive, however, independent of the accretion strength investigated. We conclude that the migration of solid accreting planets can be substantially departed from the canonical type-I prediction.

Piotr. M. Kowalski, Steve Lange, Guido Deissmann et al.

Computational modeling is an important aspect of the research on nuclear waste materials. In particular, atomistic simulations, when used complementary to experimental efforts, contribute to the scientific basis of safety case for nuclear waste repositories. Here we discuss the state-of-the-art and perspectives of atomistic modeling for nuclear waste management on a few cases of successful synergy of atomistic simulations and experiments. In particular, we discuss here: (1) the potential of atomistic simulations to investigate the uranium oxidation state in mixed valence uranium oxides and (2) the ability of cementitious barrier materials to retain radionuclides such as 226Ra and 90Sr, and of studtite/metastudtite secondary peroxide phases to incorporate actinides such as Np and Am. The new contribution we make here is the computation of the incorporation of Sr by C-S-H (calcium silicate hydrate) phases.

Jamshed Anwar, Christian Leitold, Baron Peters

Solid solutions, structurally ordered but compositionally disordered mixtures, can form for salts, metals, and even organic compounds. The NaCl-KCl system forms a solid solution at all compositions between 657°C and 505°C. Below a critical temperature of 505°C, the system exhibits a miscibility gap with coexisting Na-rich and K-rich rocksalt phases. We calculate the phase diagram in this region using the semi-grand canonical Widom method, which averages over virtual particle transmutations. We verify our results by comparison with free energies calculated from thermodynamic integration and extrapolate the location of the critical point. The calculations reproduce the experimental phase diagram remarkably well and illustrate how solid-solid equilibria and chemical potentials, including those at metastable conditions, can be computed for materials that form solid solutions.