A study on sound quality of vehicle engine sportiness using factor analysis

Journal of Mechanical Science and Technology - For those who enjoy driving, the “sportiness” the engine sound is an important point to consider. However, owing to its abstractness,...     

Room‐Temperature Metallic Fusion‐Induced Layer‐by‐Layer Assembly for Highly Flexible Electrode Applications

To fabricate flexible electrodes, conventional silver (Ag) nanomaterials have been deposited onto flexible substrates, but the formed electrodes display limited electrical conductivity due to residual bulky organic ligands, and thus postsintering processes are required to improve the electrical conductivity. Herein, an entirely different approach is introduced to produce highly flexible electrodes with bulk metal–like electrical conductivity: the room‐temperature metallic fusion of multilayered silver nanoparticles (NPs). Synthesized tetraoctylammonium thiosulfate (TOAS)‐stabilized Ag NPs are deposited onto flexible substrates by layer‐by‐layer assembly involving a perfect ligand‐exchange reaction between bulky TOAS ligands and small tris(2‐aminoethyl)amine linkers. The introduced small linkers substantially reduce the separation distance between neighboring Ag NPs. This shortened interparticle distance, combined with the low cohesive energy of Ag NPs, strongly induces metallic fusion between the close‐packed Ag NPs at room temperature without additional treatments, resulting in a high electrical conductivity of ≈1.60 × 10⁵ S cm^?1 (bulk Ag: ≈6.30 × 10⁵ S cm^?1). Furthermore, depositing the TOAS–Ag NPs onto cellulose papers through this approach can convert the insulating substrates into highly flexible and conductive papers that can be used as 3D current collectors for energy‐storage devices.     

Affinity propagation‐based interference‐free clustering for wireless sensor networks

Wireless sensor networks (WSNs), eg, industrial WSNs, require reliability and real‐time communication. Clustering technique together with schedule‐based access can provide the benefits, such as energy saving, reliability, and timeliness. However, integrating above two technologies into WSNs requires sophistical time slot allocation mechanism. To simplify the time slot allocation, the paper proposes a distributed interference‐free clustering algorithm for WSNs. The algorithm is inspired by affinity propagation (AP) clustering algorithm. By adapting and improving the original AP algorithm, the proposed clustering algorithm aims to jointly optimize energy saving and coverage issues while providing interference free between clusters. The performance analysis demonstrates that it can achieve high receiving rate (reliability), low delay (real time), and low‐energy consumption.     

Printable and Rewritable Full Block Copolymer Structural Color

Structural colors (SCs) of photonic crystals (PCs) arise from selective constructive interference of incident light. Here, an ink‐jet printable and rewritable block copolymer (BCP) SC display is demonstrated, which can be quickly written and erased over 50 times with resolution nearly equivalent to that obtained with a commercial office ink‐jet printer. Moreover, the writing process employs an easily modified printer for position‐ and concentration‐controlled deposition of a single, colorless, water‐based ink containing a reversible crosslinking agent, ammonium persulfate. Deposition of the ink onto a self‐assembled BCP PC film comprising a 1D stack of alternating layers enables differential swelling of the written BCP film and produces a full‐colored SC display of characters and images. Furthermore, the information can be readily erased and the system can be reset by application of hydrogen bromide. Subsequently, new information can be rewritten, resulting in a chemically rewritable BCP SC display.     

Clustering of platinum atoms into nanoscale particle and network on NaY zeolite

Platinum has been supported on NaY zeolite by ion exchange of Pt(NH₃)₄ ²⁺. Clustering of Pt atoms into a 1 nm cluster, and three-dimensional quantum-size wire (3 nm thick) network (greater than 100 nm) from reduction of the Pt species has been investigated by extended X-ray absorption fine structure transmission electron microscopy and xenon adsorption measurements.     

Purification of surfactant from lung washings and washings contaminated with blood constituents

A rapid and simple method capable of purifying surfactant from rabbit alveolar washings and from washings contaminated with serum has been developed. The sample, containing 16% NaBr, is placed beneath a two-layer discontinuous gradient of NaBr. After centrifugation, the surfactant is found near the top of the gradient tube at a density of 1.085 at 4 C while the contaminating material remains near the bottom. The lipid composition of surfactant from lung washings of normal animals isolated by this method compares quite favorably with surfactant isolated by much more elaborate and time consuming methods. Surfactant purified from mixtures of³H-palmitate labeled rabbit serum and lung washings (1.6 mg serum phospholipid: 1 mg washing phospholipid) contained less than 3% of the phospholipid radioactivity. The phospholipid composition of this band was quite similar to that of surfactant from normal lung washings, but the protein content was much higher. A second density gradient centrifugation removed 90% of this protein resulting in a surfactant fraction with a phospholipid to protein ratio similar to that of surfactant from normal lung washings. These findings demonstrate that this purification method is capable of removing a large proportion of both serum phospholipids and proteins from lung washings contaminated with serum, making this method uniquely suitable for evaluation of surfactant in pathologic conditions of the lung.     

Steady-flow characteristics and its influence on spray for direct injection diesel engine

Flow and spray characteristics are critical factors that affect the performance and exhaust emissions of a direct injection diesel engine. It is well known that the swirl control system is one of the useful ways to improve the fuel consumption and emission reduction rate in a diesel engine. However, until now there have only been a few studies on the effect of flow on spray. Because of this, the relationship between the flow pattern in the cylinder and its influence on the behavior of the spray is in need of investigation. First, in-cylinder flow distributions for 4-valve cylinder head of Dl (Direct Injection) Diesel engine were investigated under steady-state conditions for different SCV (Swirl Control Valve) opening angles using a steady flow rig and 2-D LDV (Laser Doppler Velocimetry). It was found that swirl flow was more dominant than that of tumble in the experimented engine. In addition, the in-cylinder flow was quantified in terms of swirl/tumble ratio and mean flow coefficient. As the SCV opening angle was increased, high swirl ratios more than 3.0 were obtained in the case of SCV -70ΰ and 90ΰ. Second, spray characteristics of the intermittent injection were investigated by a PDA (Phase Doppler Anemometer) system. A Time Dividing Method (TDM) was used to analyze the microscopic spray characteristics. It was found that the atomization characteristics such as velocity and SMD (Sauter Mean Diameter) of the spray were affected by the in-cylinder swirl ratio. As a result, it was concluded that the swirl ratio improves atomization characteristics uniformly.     

Polyurethanes based on isophorone diisocyanate trimer and polypropylene glycol crosslinked by thermal reversible diels alder reactions

Crosslinked self‐healing polyurethanes based on Diels–Alder (DA) reaction were synthesized from a trifunctionalized isophorone diisocyanate (IPDI) and polypropyleneglycol prepolymer with furfuryl alcohol and a commercial bismaleimide. The DA reaction was followed by FTIR spectroscopy at different temperatures. From the infrared results the kinetic rate constants as well as the DA reaction reversibility were established. The retro DA reaction (rDA) and its reversibility was monitored by DSC according to the enthalpy involved in the process. The obtained polymers exhibited thermosetting properties at room temperature, although they showed thermoplastic behavior at high temperatures. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44543.