Search

Two-stroke, low-speed diesel engines are widely used in large ships due to their good performance and fuel economy. However, there have been few studies of the effects of lubricating oils on the vibration of two-stroke, low-speed diesel engines. In this work, the effects of three different lubricating oils on the vibration characteristics of a low-speed engine are investigated, using the frequency domain, time-frequency domain, fast Fourier transform (FFT) and short-time Fourier transform (STFT) methods. The results show that non-invasive condition monitoring of the wear to a cylinder liner in a low-speed marine engine can be successfully achieved based on vibration signals. Both the FFT and STFT methods are capable of capturing information about combustion in the cylinder online in real time, and the STFT method also provides the ability to visualise the results with more comprehensive information. From the online condition monitoring of vibration signals, cylinder lubricants with medium viscosity and medium alkali content are found to have the best wear protection properties. This result is consistent with those of an elemental analysis of cylinder lubrication properties and an analysis of the data measured from a piston lifted from the cylinder after 300 h of engine operation.

Summary: In this paper, a modified consensus protocol algorithm is proposed for controlling a group of identical unmanned aerial vehicles (UAVs), which have been subjected to interfering signals during coordinate information exchange, using an unknown parameter in the consensus protocol. The maximum levels of interfering signals in the proposed protocol were adjusted by incorporating a hysteresis function with a dead zone consistent with the initial coordinates and the interfering signal levels. An adaptation algorithm is proposed to address a priori uncertainty regarding the consensus parameters, involving the correction of an unknown parameter by eliminating control signals exhibiting false sign changes. This correction relies on the coordinates in the phase plane, indicating that the delay in maneuver execution occurs at the beginning of the maneuver. Furthermore, by modeling synchronized motion, UAV group consensus is demonstrated for an ideal case devoid of a priori uncertainty regarding control protocol parameters, interfering signals, or consequences. The convergence of the adaptation algorithm was assessed by defining a vector function to track parameter changes during tuning. The monotonically decreasing nature of the resulting curve, along with the finite duration of the tuning process, provides confirmation of the convergence of the adaptation algorithm. [ABSTRACT FROM AUTHOR]

Cation-disordered rocksalt (DRX) oxides show promise as lithium-ion battery cathodes due to their high theoretical capacity derived from anionic redox. However, the challenges of poor anionic redox reversibility, causing oxygen loss and voltage hysteresis, lead to rapid capacity decay. This study employs a dual-functional urea treatment on Li1.2Ti0.4Mn0.4O2 DRX cathodes, generating oxygen vacancies in the subsurface and a protective carbon nitride layer on the surface through interface reactions. Characterization via X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy confirms these alterations. The presence of oxygen vacancies reduces the average Mn valence, increasing the capacity contributed by Mn and enhancing the reversibility of anionic oxygen redox, thus curbing oxygen loss. Additionally, the carbon nitride layer curtails the parasitic reaction between active oxygen species and the electrolyte. Urea-treated Li1.2Ti0.4Mn0.4O2 exhibits enhanced electrochemical performance, retaining a higher capacity (151 mAh⋅g−1, 80.3% of capacity retention) after 50 cycles compared to neat Li1.2Ti0.4Mn0.4O2 (117 mAh⋅g−1, 64.6% retention). Furthermore, the treatment improves lithium-ion diffusion and rate capability. This dual-functional urea approach presents a promising strategy for enhancing DRX cathode materials and advancing high-performance lithium-ion batteries. [ABSTRACT FROM AUTHOR]

In this work, a chemical grafting polymerization method was employed to synthesize EHPMC-g-PANI self-supporting films. Polyaniline (PANI) was grafted onto hydroxypropyl methylcellulose (HPMC) modified with epichlorohydrin (EPHMC) to obtain an EHPMC-g-PANI aqueous dispersion, which was subsequently dried to form the self-supporting films. The introduction of HPMC, with its excellent film-forming ability and mechanical strength, successfully addressed the poor film-forming ability and mechanical properties intrinsic to PANI. Compared to in situ polymerized HPMC/PANI, the EHPMC-g-PANI exhibited significantly improved storage stability. Moreover, the fabricated EHPMC-g-PANI films displayed a more uniform and smoother morphology. The conductivity of all the films ranged from 10−2 to 10−1 S/cm, and their tensile strength reached up to 36.1 MPa. These results demonstrate that the prepared EHPMC-g-PANI holds promising potential for applications in various fields, including conductive paper, sensors, and conductive inks. [ABSTRACT FROM AUTHOR]

Efficient detection of chemical oxygen demand (COD) is crucial for effective pollution prevention. Traditional Cu‐based electrodes, widely utilized for COD sensors suffer from issues related to low activity and stability. This study introduced a novel approach by employing a copper foam‐supported metal‐organic frameworks (Cu‐MOF), synthesized through a solvothermal method, which is subsequently pyrolyzed to yield a carbon‐capsulated CuOx/Cu foam electrode. Cyclic voltammetry analysis demonstrated that the carbon‐capsulated CuOx/Cu foam electrode exhibited superior redox activity, notably generating an increased amount of Cu(III) species. This enhancement significantly contributed to the electrocatalytic oxidation of organic compounds. The developed electrode demonstrated a wide linear detection range of 5–600 ppm, with a low detection limit of 0.96 ppm (S/N=3) for COD sensing. Notably, the sensor exhibited excellent anti‐interference capabilities, desirable reproducibility, and stability. The proposed method was successfully applied to determine COD in real water samples. Comparative analysis with the standard potassium dichromate method revealed high accuracy and a low relative error (2.89 %–6.72 %). This innovative approach holds promise for rapid and accurate COD detection, presenting a valuable contribution to environmental monitoring and water quality assessment. [ABSTRACT FROM AUTHOR]

The book "International Discourses of Authoritarian Populism: Varieties and Approaches" edited by Ludwig Deringer and Liane Ströbel explores the rise of authoritarian populism and its impact on democratic structures globally. The collection of fifteen chapters examines populist discourses from various perspectives, including political science and linguistics. The book analyzes specific cases of authoritarian populism in countries such as the United States, Italy, Finland, France, Spain, Hungary, and Venezuela. It also delves into the use of rhetoric, media manipulation, and the portrayal of immigrants in populist discourse. The volume provides valuable insights into the phenomenon of populism and its implications for society. [Extracted from the article]

The next-generation 650 MHz solid state power amplifier designed by the Institute of Modern Physics will utilize 24 modules with an output power of 60 kW. The outputs of each of the 12 modules will be combined using a 12-in-1 rectangular cavity combiner integrated into the rack. This cavity combiner, requiring only a single stage to combine power, is characterized by a minimal power loss and a high combining efficiency. The input couplers of the combiner are adjustable to change the number of combination channels. In the event of one amplifier module failure, the corresponding port can be adjusted to decouple, transforming the combiner to an (N-1)-channel combiner with a combining efficiency decay of 0.2%. The prototype of the combiner has been fabricated and tested with a small signal. The combining efficiency is 98.5%. In this paper, we will validate the feasibility of the combiner from the design, simulation, and experiment. [ABSTRACT FROM AUTHOR]

The 0–1 mixed integer programming problem of binary offloading on wireless powered mobile edge computing (WP‐MEC) networks requires joint optimization of binary and continuous variables, which is computationally expensive for traditional techniques and difficult to solve within the channel coherence time under time‐varying condition. Using machine learning models to output variable values is also challenging. Hence, designing efficient and low‐complexity algorithms is crucial for optimal network performance. This paper focuses on the computation latency of the FDMA‐based WP‐MEC network and proposes a task‐offloading algorithm to minimize the total completion delay (TCD). The TCD minimization is modelled as a 0–1 MIP problem and is decomposed into a master problem of optimizing the offloading decision and the sub‐problem of optimizing other parameters under a given offloading decision. The sub‐problem is solved using optimization method, while the master problem is solved using a deep reinforcement learning algorithm. Simulation results show that the proposed algorithm can achieve almost minimal TCD with low complexity. [ABSTRACT FROM AUTHOR]