Loading Rate Research Articles

Anisotropic MXene@polydopamine- and Dialdehyde Carboxymethyl Cellulose-Modified Collagen Aerogel Supported Form-Stable Phase Change Composites for Light-To-Heat Conversion and Energy Storage.

As a renewable alternative heat source, the inherently intermittent feature of solar energy needs to be coordinated by reliable energy conversion and storage systems for utilizing the most abundant solar energy. Phase change materials (PCMs) are supposed to be advanced mediums for storing a great deal of heat generated by solar light. However, PCMs cannot effectively absorb and utilize solar energy due to leakage, low photothermal conversion efficiency, and poor thermal conductivity. Herein, we developed a collagen-based aerogel modified by dialdehyde carboxymethyl cellulose and polydopamine-modified two-dimensional transition-metal carbide/nitride (MXene@PDA) through bidirectional freeze-drying technology for supporting PCMs, which exhibited anisotropy in structure and properties. In particular, the thermal conductivity of the aerogel was 0.0871 W/(m·K) in the axial direction and 0.0504 W/(m·K) in the radial direction, demonstrating its anisotropic thermal insulation performance. Moreover, the final aerogel composite PCMs had been obtained via impregnating the obtained aerogel supporting matrix into polyethylene glycol (PEG) and hydrophobic treatment of polydimethylsiloxane, which exhibited outstanding solar-thermal conversion ability, good thermal storage capacity, advanced leakage-proof property, and antifouling performance. The loading rate of PEG was as high as 92.2%, and the melting enthalpy was 132.6 J/g. Most importantly, the water contact angle was evaluated to be 156.8°, indicating its superior antifouling performance. This material has intensive application prospects in the fields of solar energy collection, conversion, and storage.

Crushing responses and energy absorption characteristics of the dynamic stiffening porous material subjected to different strain rates

Porous material (PM) has excellent energy absorption performance and is widely used as an impact-energy absorber. However, the PM may provide little utility when the impact conditions change. Shear stiffening gel (SSG) with an extremely strong viscosity effect can be as a dynamic responding fortifier to overcome the limitation of PMs. In this paper, a rate-dependent, smart energy-absorbing material (SSG/PM) is fabricated by incorporating SSG that is reinforced with CaCO3 particles onto the PM. Aided by the dynamic compression experiments at the strain rate range of 0.001 to 100 s−1, both SSG/PM and neat PM are assessed and compared for crushing performance. Results reveal that the SSG/PM exhibits a pronounced dynamic stiffening characteristic in response to various strain rates owing to the rate-dependent phase transition of embedded SSG, thereby contributing to enhancing the PM skeleton's ability to withstand deformation. The SSG/PM displays a noteworthy boost in energy absorption (up to 831.98 %). Moreover, the influence of loading rate, particle mass fraction, and PM aperture size are also examined. The findings indicate that its crushing resistance and energy absorption capability are enhanced with the increase in strain rate, demonstrating the ability to adapt to various dynamic scenarios. The use of a higher particle mass fraction and smaller aperture size helps to improve the energy absorption capability of the SSG/PM. Additionally, quantitative energy analysis is implemented in which the energy dissipation mechanisms of the SSG/PM are attributed to the synergistic interaction of skeleton deformation, shear stiffening effects, and particle enhancement. It is ascertained that as the loading rate increases, the shear stiffening effect continues to strengthen; the particle content effect exhibits a rising-falling trend; while the skeleton deformation shows a rate-independent feature. This study sheds light on the crushing behaviors and corresponding energy dissipation mechanisms of SSG-based composites, thereby providing valuable insights for the design of SSG-based composites.

Long-term and multiscale assessment of methanogenesis enhancement mechanisms in magnetite nanoparticle-mediated anaerobic digestion reactor

Magnetite nanoparticles (Fe3O4-NPs) have been demonstrated to be involved in direct interspecies electron transfer between syntrophic bacteria, yet a comprehensive assessment of the ability of Fe3O4-NPs to cope with process instability and volatile fatty acids (VFAs) accumulation in scaled-up anaerobic reactors is still lacking. Here, we investigated the start-up characteristics of an expanded granular sludge bed (EGSB) with Fe3O4-NPs as an adjuvant at high organic loading rate (OLR). The results showed that the methane production rate of R1 (with Fe3O4-NPs) was approximately 1.65 folds of R0 (control), and effluent COD removal efficiency was maintained at approximately 98.32% upon 20 kg COD/(m3·d) OLR. The components of volatile fatty acids are acetate and propionate, and the rapid scavenging of propionate accumulation was the difference between R1 and the control. The INT-ETS activity of R1 was consistently higher than that of R0 and R2, and the electron transfer efficiencies increased by 68.78% and 131.44%, respectively. Meanwhile, the CV curve analysis showed that the current of R1 was 40% higher than R3 (temporary addition of Fe3O4-NPs), indicating that multiple electron transfer modes might coexist. High-throughput analysis further revealed that it was difficult to reverse the progressive deterioration of system performance with increasing OLR by simply reconfiguring bacterial community structure and abundance, demonstrating that the Fe3O4-NPs-mediated DIET pathway is a prerequisite for establishing multiple electron transfer systems. This study provides a long-term and multi-scale assessment of the gaining effect of Fe3O4-NPs in anaerobic digestion scale-up devices, and provides technical support for their practical engineering applications.

Investigation on the loading rate dependence of electromechanical properties of graphene-cement composites under compressive loading

In this paper, the dependence of the electromechanical properties of graphene-cement composites on the loading rate is studied by combining experiment and theory. The graphene-cement composites are prepared using a wet dispersion technique combined with surfactant assist and ultrasonication treatment. Both monotonic and cyclic compressive experiments with different loading rates are conducted on the graphene-cement composites with different graphene contents to measure their mechanical, electrical and piezoresistive properties. The optimum dosage of graphene in cement matrix is about 0.05 wt%, which can increase the compressive strength by 35.7 % and 34.1 %, and decrease the electrical resistivity to 1.43 and 3.48 × 105 Ω•cm, respectively, after 14 and 28 d curing periods. The uniform dispersion of graphene with less layers endows the graphene-cement composites with very low percolation threshold of electrical conductivity (0.007 wt%), stable piezoresistive response, and good reproducibility. Furthermore, the mechanism of the loading rate on the strain sensing behavior is discussed, and a rate dependent theoretical model of resistance change is proposed to quantitatively predict the electromechanical responses. This study provides guidelines for the fabrication of highly strain-sensitive graphene-cement composites and the rate-dependent evaluation of their electromechanical properties in the fields of intelligent construction.

CO2 emissions of fuel-cell battery hybrid system for large ships

ABSTRACT The needs of solid oxide fuel cells (SOFC) and batteries in large ships are analyzed by estimating the amount of fuel consumption and CO2 emissions. Three types of systems are proposed: 1) fuel cells-battery-generator engine system, 2) battery-generator engine system, and 3) generator engine system. This study is based on the time-varying electric power demand and adopted the sequential quadratic programming (SQP) method to find the optimal power distribution of mixed power sources. CO2 emissions in the SOFC hybrid system are 11.6% lower than in the conventional generator engine system, and those in the battery-generator engine system are 5.1% lower than in the conventional system. The reduction of CO2 emissions come from three factors: the operation of the generator engine at a relatively high load rate, the battery sharing the operation of the generator engine, and the high efficiency of the SOFC running. The SOFC hybrid system can be a sustainable technology in large vessels.

Enhancing methane yield and shifting microbial communities in anaerobic reactors treating lipid-rich dairy wastewater through exogenous lipase addition

This study explores a novel enzymatic pretreatment approach in anaerobic reactors for dairy wastewater, using lipase AY Amano to enhance methane production and modify microbial and archaeal community composition. Batch and semi-batch reactors with a total volume of 2000 mL were used to treat dairy wastewater with initial COD of 2000 and 15,000 mg L−1, respectively. In a new novel approach, the semi-batch reactors underwent a three-phase operation: 30 days of acclimation, 30 days of rest, and 30 days of active operation. Adding lipase (0.05% wv−1) as a pretreatment significantly increased methane yield over the 90 days by 135–138% compared with the control (without enzyme addition). The organic loading rate reached 0.22 g COD day−1 L−1. Furthermore, 30 days after the end of the semi-batch reactor approach (120 days from the start), reusing sludge in batch reactors increased methane yield by 114–122% compared to the control. This increase was linked to the emergence and shift of new methanogenic communities within the sludge. Integrating hydrolytic enzymes into the anaerobic treatment enhances performance and sustainability by fostering methanogen-enriched microbial communities. This is crucial for maximizing methane production but may increase costs, requiring further economic feasibility research.

Effects of folded fissure properties on tunnel model failure: Experiments and numerical simulations

Natural folded fissures commonly exist rather than simple straight fissures in rock masses surrounding tunnels. The presence of folded fissures significantly affects the fracture processes and failure modes of tunnel structures, thereby affecting their safety and stability. However, the research in this area is limited. Given this, this study fabricates city-gate section tunnel specimens containing folded fissures of various dip angles (α) and orientation angles (β), utilising 3D sand printing with sand and furan resin as matrix materials. Uniaxial compression fracture tests were conducted at a loading rate of 0.3 mm/min on these specimens using a digital image correlation technique to assess the impact of folded fissures on the mechanical properties and failure modes of the tunnel structures. Additionally, the improved smoothed particle hydrodynamics (SPH) method was used for damage evolution simulations during interactions between folded fissures and tunnels, and the simulation results were compared with the experimental results to verify the correctness of the method. The results show that for folded fissures, wing cracks and anti-wing cracks initiate not only from the ends but also from the bends of the fissures, whereas for straight fissures, they appear only at the fissure ends. Except for β = 0°, the interaction between folded fissures and tunnels generally results in the formation of a crack connecting the folded fissure upper end with tunnel, and the connection position varies with β. Different β values of folded fissures also influence the appearance and morphologies of top major cracks, underside major cracks, side cracks, and corner cracks around tunnels. As α increases, the overlap point of the crack and the tunnel moves from the tunnel corner to the tunnel crown. Moreover, folded fissures significantly affected the peak strength of the tunnel structures. As β increases, the peak strength first decreases, then increases, and finally decreases, reaching a minimum of 3.58 MPa at β = 90°. However, the peak strength differences are not evident under different α values. Finally, the influence of folded fissures on the cracking mechanism of the tunnel models is discussed in detail. This study provides insights into the impact of folded fissures on tunnel fracture modes and offers a reference for the application of SPH to reveal the underlying failure mechanisms of tunnel structures.

Methanogenic degradation of long-chain fatty acids associated with syntrophic microbial dynamics during thermophilic AnMBR treatment of lipid-rich dairy wastes

Anaerobic membrane reactors (AnMBRs) have been applied to effectively treat dairy wastes because they can address the drawbacks of sludge flotation and biomass washout. However, when dairy wastes contain considerable proportion of lipids, any anaerobic systems will likely encounter challenges with long-chain fatty acid (LCFA) inhibition. In this study, a thermophilic AnMBR was operated to treat dairy processing wastewater (DPW) plus ice cream waste (ICW). To evaluate the impact of LCFAs, the lipid-rich ICW was gradually introduced at different levels (0, 5, 10, and 20 %) into the AnMBR, along with a stepwise increase in lipid loading rate (LLR) from 0.22 to 11.24 g lipid/L/d. The results of biomethanation revealed that the AnMBR could be successfully operated when the LLR was maintained at 5.73 g lipid/L/d with a lipid/VS ratio of 50.22 % in the feedstock. However, at ultra-high LLR of 11.24 g lipid/L/d (20 % ICW added), a significant inhibitory effect on methane yields was observed, resulting in a reduction of 56.90 %. Dynamic analysis of the LCFAs profiled that a lower degradation rate was an important factor contributing to LCFA accumulation, and the inhibition concentration of various LCFAs was identified. Based on microbial evolution and co-occurrence network results, potential syntrophic partnerships between LCFA-degrading bacteria and methanogens were proposed. The responsible enzyme genes in the LCFA-degrading, acetoclastic, and hydrogenotrophic methanogenic pathways played crucial roles in LCFA inhibition and degradation. These findings offer practical insights for the efficient methanogenic treatment of lipid-rich wastes.

A FDEM study on the mechanical properties and failure behavior of soft-hard interbedded rocks considering the size effect

Soft–hard interbedded rocks are widely distributed at the Earth’s surface, and their mechanical properties and failure behavior directly affect the stability of local tunnel and slope engineering projects. Previous studies have rarely considered the influence of size effects on the mechanical properties and failure behavior of such rocks. Therefore, this paper used the combined finite–discrete element numerical method (FDEM) to study the mechanical properties and failure behavior of soft–hard interbedded rock samples considering the size effect. First, appropriate input parameters were calibrated and verified by using a new parameter calibration method. Second, the effects of the element size and loading rate were studied to obtain appropriate model parameters. Finally, the effects of the layer number, sample size, and height–diameter ratio of composite rock samples on their mechanical properties and failure behavior at different layer dip angles and layer thickness ratios were investigated. The results support the following findings: (1) For the composite rock samples with a layer thickness of 10 mm, reliable simulation results can be obtained by using a 2.2 mm element size, and the loading rate should not exceed 0.2 m/s in FDEM numerical modeling. (2) The number of layers in the sample should be at least 5, and when the height–diameter ratio is a constant 2.0, the height of the sample should not be less than 110 mm. (3) As the height–diameter ratio of the composite rock samples increases, both the compressive strength and elastic modulus decrease for all layer dip angles considered, but the rock failure mode changes for layer dip angles of 15–75°; in addition, the sample size effect is most significant for layer dip angles of 60° and 75°. (4) Taking horizontally layered composite rock samples as examples, both the compressive strength and elastic modulus of samples with different layer thickness ratios decrease with increasing height–diameter ratio and their failure modes also depend on the height–diameter ratio.

Effects of temperature and loading rate on the shear performance of GFRP-steel single-lap joints

This research examines how the shear properties of glass fiber-reinforced polymer (GFRP) and steel single-lap joints react under various temperatures (−25, 0, 25, 50, and 100℃) and loading speeds (0.625, 1.25, 2.5, and 5.0 m/s). The GFRP sheets, aligned unidirectionally, were produced using vacuum-assisted resin transfer molding and were then adhesively attached to steel plates with epoxy resin. The assemblies were subjected to a high-speed servo-hydraulic testing apparatus for evaluation. The results indicate that the joint's performance is relatively unaffected by changes in the loading speed, but the overall toughness tends to decrease at higher speeds. However, the adhesive bond strength increases when temperatures are between −25 and 50℃ but diminishes as temperatures rise from 50 to 100℃. Most samples exhibited debonding at the steel-adhesive interface under varied speeds and colder temperatures, whereas debonding at the GFRP-adhesive interface was more prevalent at elevated temperatures. These insights are vital for both theoretical analyses and practical implementations of GFRP-steel single-lap joints in environments subject to extreme loading conditions and temperatures.

KPV and RAPA Self-Assembled into Carrier-Free Nanodrugs for Vascular Calcification Therapy.

Cardiovascular disease (CVD) is a leading cause of death globally, and vascular calcification (VC) is an important independent risk factor for predicting CVD. Currently, there are no established therapeutic strategies for the treatment of VC. Although recognized combination therapies of nanomedicines can provide effective strategies for disease treatment, the clinical application of nanomedicines is limited because of their complex preparation processes, low drug loading rates, and unpredictable safety risks. Thus, developing a simple, efficient, and safe nanodrug to simultaneously regulate inflammation and autophagy may be a promising strategy for treating VC. Herein, an anti-inflammatory peptide (lysine-proline-valine peptides, KPV) and the autophagy activator rapamycin (RAPA) are self-assembled to form new carrier-free spherical nanoparticles (NPs), which shows good stability and biosafety. In vivo and in vitro, KPV-RAPA NPs significantly inhibit VC in mice compared to the other treatment groups. Mechanistically, KPV-RAPA NPs inhibit inflammatory responses and activated autophagy. Therefore, this study indicates that the new carrier-free KPV-RAPA NPs have great potential as therapeutic agents for VC combination therapy, which can promote the development of nanodrugs for VC.

Simulation and experimental analysis of dynamic thermal rise relaxation characteristics for dry-type distribution transformer

Abstract The temperature distribution characteristics of dry-type distribution transformers reflect their overall performance and quality. Distribution transformer daily load changes dramatically, its temperature fluctuates within a certain range. However, most of the research results on transformer temperature rise focus on the steady-state temperature characteristics of transformers, and lack of research related to dynamic temperature rise characteristics. This paper carries out a multi-physics coupling simulation and experimental verification of the dynamic temperature rise relaxation characteristics. The simulation uses the “electromagnetic-flow-thermal” multi-physics coupling analysis method to simulate the steady-state temperature rise characteristics and dynamic temperature rise relaxation characteristics of windings under different load rates. Then, this paper also explores the correlation between the dynamic temperature rise relaxation characteristics and load rate at the typical positions of high-voltage windings and low-voltage windings. The results show that the temperature rise of the winding shows the law of increasing the saturation index function with the increase of the load application time at any load rate. A quantitative characterization model of dynamic temperature rise relaxation behavior at different positions of transformer windings is constructed. It is found that the steady-state temperature rise value of different parts of the winding increases regularly as a power function with the increase of load rate, while the constant value of dynamic temperature rise relaxation time in different parts of the winding decreases as a power function with the increase of load rate. The verification results of the quantitative characterization model of dynamic temperature rise relaxation behavior show that the maximum error of the measured and theoretical steady-state temperature rise value is only 1.56 K, and the maximum error of the constant value of dynamic temperature rise relaxation time is only 0.082 h. These findings provide valuable insights into the performance and quality of dry-type distribution transformers, and can help improve their design and operation for better efficiency and safety.

A Flexible Multifunctional Cyanoethyl-Modified Bacterial Cellulose Nanofiber Framework for High-Energy and High-Power Density Aqueous Li-Ion Batteries.

Aqueous rechargeable lithium-ion batteries (ARLIBs) are extensively researched due to their inherent safety, typical affordability, and potential high energy density. However, fabricating ARLIBs with both high energy density and power performance remains challenging. Herein, based on cyanoethyl-modified bacterial cellulose nanofibers (CBCNs), a multifunctional fast ion transport framework is developed to construct the flexible free-standing ARLIBs with high areal loading and excellent rate performance. Benefiting from the unique merits of CBCNs, such as ultra-high aspect ratio, excellent toughness, superior adhesion, good lithiophilicity and ideal stability, the flexible free-standing and highly robust electrodes are fabricated and exhibit a long-term stable cycling of 1200 cycles with a high specific capacity of 117 mAh∙g-1 at 15 C. Remarkably, the corresponding full cell with the free-standing high mass loading (45.5 mg∙cm-2) electrodes under the condition of ultra-low addition of battery binder demonstrates a cycle lifespan of over 1000 cycles with a specific capacity of 120 mAh∙g-1 and a capacity decay as low as 0.03% per cycle, which is far superior to those of almost all previous reports. This work provides a strategy for constructing ARLIBs with high energy density and power performance by introducing a unique fast ion transport nanofiber framework.

Tea saponin-Zein binary complex as a quercetin delivery vehicle: preparation, characterization, and functional evaluation

In this study, in order to solve the application problems of poor water solubility and low bioavailability of quercetin, we prepared a nano-delivery system with core-shell structure by anti-solvent method, including a hydrophilic shell composed of tea saponin and a hydrophobic core composed of Zein, which was used to improve the delivery efficiency and biological activity of quercetin. Through the optimal experiments, the loading rate and encapsulation rate of nanoparticles reached 89.41 % and 7.94 % respectively. And the water solubility of quercetin is improved by 30.16 times. At the same time, the quercetin acted with Zein through non-covalent interaction and destroyed its spatial network through structural characterization, while tea saponin covered the surface of Zein through electrostatic interaction, making it change into amorphous state. In addition, the addition of tea saponin makes the nanoparticles remain stable under the changes of external environment. During simulating gastrointestinal digestion procedure, ZQTNPs has higher release rate and bioavailability than free quercetin. Importantly, ZQTNPs can overcome the limitations of a single substance through synergy. These results will promote the innovative development of quercetin precision nutrition delivery system.

Exploring the strain rate influence on shear yield behavior of acrylonitrile-butadiene-styrene: Experimental and numerical study

Most experimental and numerical studies are limited to examining the effect of strain rate on the compressive and tensile yield behavior of Acrylonitrile-Butadiene-Styrene (ABS), an amorphous material of significant industrial relevance, rather than its shear yield behavior; therefore, this study is dedicated to addressing this notable gap in the literature by exploring the effect of strain rate on the shear yield behavior of ABS. To this end, shear tests were carried out using the Wyoming version of the Iosipescu (V-notched) shear test fixture at five distinct loading rates, ranging from 5 × 10−3 to 1 × 101 mm/s, which correspond to strain rates between 5.5 × 10−4 s−1 and 7 × 10−1 s−1. Shear strain distributions in the specimens were measured using the Digital Image Correlation (DIC) technique. The shear test results not only revealed a substantial increase in the shear yield strength of ABS with increasing strain rate, but also demonstrated that the shear yield strength of ABS is more sensitive to strain rate than its compressive and tensile yield strengths. The findings of the study also suggested that using shear-tension test data pairs at the same strain rates is more effective for determining the hydrostatic pressure sensitivity parameter than using tension-compression and shear-compression test data pairs. The experimental results were validated against numerical predictions obtained through finite element analyses employing an elastic-viscoplastic constitutive model, which comprehensively accounted for non-linear material properties, geometric complexities, and non-linearities arising from boundary contacts.

The Valorization of Fruit and Vegetable Wastes Using an Anaerobic Fixed Biofilm Reactor: A Case of Discarded Tomatoes from a Traditional Market

Tomato waste, characterized by high organic matter and moisture content, offers a promising substrate for anaerobic digestion, though rapid acidification can inhibit methanogenic activity. This study investigated the performance of a 10.25 L anaerobic fixed biofilm reactor for biogas production using liquid tomato waste, processed through grinding and filtration, at high organic loading rates, without external pH control or co-digestion. Four scouring pads were vertically installed as a fixed bed within a fiberglass structure. Reactor performance and buffering capacity were assessed over three stages with progressively increasing organic loading rates (3.2, 4.35, and 6.26 gCOD/L·d). Methane yields of 0.419 LCH4/gCOD and 0.563 LCH4/g VS were achieved during the kinetic study following stabilization. Biogas production rates reached 1586 mL/h, 1804 mL/h, and 4117 mL/h across the three stages, with methane contents of 69%, 65%, and 72.3%, respectively. Partial alkalinity fluctuated, starting above 1500 mg CaCO3/L in Stage 1, dropping below 500 mg CaCO3/L in Stage 2, and surpassing 3000 mg CaCO3/L in Stage 3. Despite periods of forced acidification, the system demonstrated significant resilience and high buffering capacity, maintaining stability through hydraulic retention time adjustments without the need for external pH regulation. The key stability indicators identified include partial alkalinity, effluent chemical oxygen demand, pH, and one-day cumulative biogas. This study highlights the effectiveness of anaerobic fixed biofilm reactors in treating tomato waste and similar fruit and vegetable residues for sustainable biogas production.

Loading rate effects on multifiber pullout resistance of smooth steel fibers in ultra-high-performance concrete

This study investigated the multi-fiber pullout resistance of high-strength smooth steel fibers embedded in ultra-high-performance concrete (UHPC) at different loading rates. To discover the source of the fiber group effect on fiber pullout resistance, multi-fiber pullout tests were employed by changing the number of fibers, fiber-to-fiber distance, and difference in embedded lengths. The main source of the fiber group effect was found to be the reduced contact pressure per fiber, in the specimens containing more fibers, generated by matrix shrinkage: the fiber pullout stress at the static loading rate (0.0167 mm/s) decreased from 786.58 to 618.59 MPa (21.4 % reduction) as the number of fibers increased from 1 to 25. The equivalent bond strength of smooth steel fiber in UHPC generally increased from 4.5–5.2 to 5.9–7.1 MPa as the loading rate increased from 0.0167 to 1.67 mm/s. The favorable rate-sensitive pullout resistance of multi-fiber pullout specimens was notably affected by the number of fibers and fiber distance: the specimens containing nine fibers with a 2.7 mm fiber distance produced the highest dynamic increase factor (1.37) owing to enhanced interactions between interfacial cracks.

Constitutive model for shape memory polymer and its thermodynamic responses in finite element analysis.

As a new intelligent polymer material, shape memory polymer (SMP) was a potential orthodontic appliance material. This study aimed to investigate the thermodynamic responses of SMP under different loads via finite element analysis (FEA). FEA specimens with a specification of 0.1 × 0.1 × 1 mm were designed. One end of the specimen was fixed, and the other was subjected to displacement load. Different loading, cooling, and heating rates were separately exerted on the specimen in its shape recovery process and used to observe the responses of the SMP constitutive model. Furthermore, specimens with various tensile elongation and sectional areas were simulated and used to elucidate their effect on shape recovering force. The specimens obtained a similar stress of 0.5, 0.44, and 1.07 Mpa for different loading, cooling, and heating rates after a long time. The shape recovering force of specimen increased from 0.0102 to 0.0315 N when the elongation improved from 10% to 40% and to 0.0408 N when the sectional areas were expanded to 0.2 × 0.2 mm. The stiffness of SMP was small at a high temperature but large at a low temperature. The effects of the loading, cooling, and heating rates on SMP can be eliminated after a long time. Furthermore, it was possible to increase the recovering force by increasing the elongation or expanding the sectional area of the specimen. The force was quadratically dependent on the elongation ratio.

Determination of Demand for LNG in Poland

This study was aimed at improving the energy efficiency of the distribution of liquefied natural gas (LNG) as shipping fuel in the southern Baltic Sea. The objective of this study was to determine the demand for LNG for maritime shipping by analyzing the distribution of the resource from the water side (ship-to-ship). LNG was chosen due to the location of the LNG terminal in Świnoujście within the analyzed water area, where a problem has arisen in the southern part of the Baltic Sea regarding fuel supply for vessels due to the lack of developed infrastructure along the coast. An analysis was conducted to optimize the size of the LNG fleet and infrastructure facilities. Seeking compliance with Annex VI to the MARPOL 73/78 Convention, adopted by the International Maritime Organization (IMO), shipowners see potential in the switch from conventional fuels to LNG. As one of the alternative solutions, it will contribute to reducing harmful emissions. Determination of the LNG distribution volume requires the identification of LNG storage facility locations, specifying the number of LNG-powered ships (broken down by type) and the number of LNG bunkering ships. The first part of this study contains a detailed analysis of the number of sea-going ships that provide services in the southern part of the Baltic Sea and the world’s number of LNG bunkering ships. The database contains a set of the characteristics required to determine the optimal demand for LNG, where LNG bunkering vessels are capable of supplying fuel within the shortest possible time and covering the shortest possible distance to LNG-powered ships. The characteristics include the type of ship, requested LNG volume, the speed of LNG bunkering ships, the distance between LNG facilities, and the loading rate (the volume of fuel received per time unit). Based on the collected data, the volume of LNG distribution was determined using MATLAB R2019a software. The remainder of this study contains a description of the conducted research and results of an analysis of the traffic density in the Baltic Sea. The results were obtained on the basis of data from the Statistical Yearbook of Maritime Economy and IALA IWRAP Mk2 2020 software. The number of LNG-powered ships and number of LNG bunkering ships were specified, and the demand for LNG for the area under analysis was determined.

Comparison of Anaerobic Co-Digestion of Food Waste and Livestock Manure at Various Mixing Ratios under Mesophilic and Thermophilic Temperatures

In this study, the optimum mixing ratio of food waste (FW) and livestock manure (LM) was investigated to improve the methane yield efficiency and prohibit the inhibition factors (organic loading rate and NH4+) from inhibiting the anaerobic co-digestion of FW and LM under mesophilic and thermophilic conditions. The research involved the following: (I) the analysis of the characteristics of FW and LM, (II) the evaluation of the potential and toxicity of the anaerobic digestion of I have confirmed that there is no problem. FW and LM using the biochemical methane potential (BMP) and anaerobic toxicity assay (ATA) tests, (III) the evaluation of the anaerobic co-digestion of FW and LM using the BMP test, and (IV) the evaluation of the optimum mixing ratio using mathematical modeling. The characteristics of FW and LM were analyzed to evaluate the theoretical methane potential and inhibition factor. The BMP test was carried out to evaluate the concentration of the biodegradable organic matter, biogas production rate, and methane yield. The ATA test was carried out to evaluate the impact of the inhibition concentration. Ultimately, mathematical models, such as a first-order reaction and a modified Gompertz model, were implemented to evaluate the optimum mixing ratio for the anaerobic co-digestion of FW and LM. FW had a higher concentration of degradable organic matter than LM. The initial operational parameters of the anaerobic digestion were determined to be appropriate at an organic matter concentration of less than 2.5 g/L and a TN concentration of 2,000 mg/L. In conclusion, as a result of evaluation through mathematical models, it was determined that anaerobic microorganisms were more sensitive to inhibitory factors under the thermophilic condition than under the mesophilic condition, and the optimum mixing ratio of FW to LM was 5:1 (vol:vol) based on kinetic results (k: 0.080; Bu: 0.23 L CH4/g VSadded; P: 100.84 mL; Rm: 10.23 mL/day; λ: 1.44 days).