This research addresses the acoustic feedback and stability performance of Active Noise Control (ANC) systems. The Filtered Cross Least Mean Square (FxLMS) algorithm is one of ANC’s most successful adaptive algorithms for reducing undesired noise. The ANC filters have their convergence speeds reduced by significant acoustic feedback, making them unstable in the worst-case scenario. It is possible to eliminate acoustic feedback using a fixed feedback neutralization filter that can be acquired offline. However, the feedback path could change over time, so we might have to make modifications often while the ANC system is online. This paper proposes two enhancements to the FxLMS algorithm to address the ANC’s performance difficulties. To address acoustic feedback problems, the first alteration improves the ANC duct’s feedback path modeling by incorporating the online Feedback Naturalization (FN) concept with an Active function normalized LMS algorithm (AF-NLMS). The second modification, the vector-decimation-based method, is proposed in this paper as a way to improve stability, convergence speed, and robustness. It is achieved by decimating the filter weight vector into small vectors and then updating each vector using the harmonic mean error of the VSS FxLMS. To ensure the enhanced effectiveness of the proposed solution, the AF-FxLMS, online-AFFNFxLMS, and HM-AFFNFxLMS algorithms are used to update the filter weights as a demonstration. The proposed method has superior noise reduction effectiveness compared to other algorithms, which indiscriminately attenuate the control filter across all frequencies. The validation of the proposed approach was achieved via simulations and experimental tests in a PVC duct ANC system, showing that robust stability can be achieved while keeping relatively good performance.

With the increase in temperature, urban areas face issues like urban heat islands. The reduction of green vegetation across urban areas has led to a tremendous rise in temperature. Many studies suggest significant cities are currently experiencing this issue to a greater extent. Many researchers are working on building paints and dyes to reduce the heat intake of the building. Organic thermochromic materials are one such alternative for building dye and stain. The main issue with using organic thermochromic materials is that they quickly degrade under sunlight, which makes them less useful for building paint. To overcome this issue, many organic thermochromic black dye materials (OTCBDM) are encapsulated with inorganic materials such as metal oxide, which block sunlight and reduce the effect of degradation. Encapsulation is achieved via the emulsification method of metal oxide. This paper deals with the single and double microencapsulation methods with different surfactant concentrations, metal oxides, and combinations thereof. Various techniques were used such as Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) with energy‐dispersive X‐ray spectroscopy technique (EDS), and differential scanning calorimeter (DSC), UV‐Vis spectroscopy, thermogravimetric analysis (TGA), and CIE Lab space analysis to determine the materials’ encapsulation and chromatic nature. The FTIR spectra suggested the absorption peaks for the Ti─OH bond (at 814, 903, and 913 cm⁻¹) and Si─OH group (at 1,084 and 1,178 cm⁻¹) for the commercial dye encapsulated with TiO₂ and SiO₂. The Ti─O─Si bonds at 1,054 and 1,145 cm⁻¹ showed for the double encapsulation of SiO₂ and TiO₂ either (i) doped or in (ii) layered structures. From the EDS analysis, we can clearly say that the presence of SiO₂ and TiO₂ indicates the encapsulation of the commercial thermochromic black dye material. The SEM micrographs of the TiO₂ encapsulation of OTCBDM seem more promising and uniform core–shell structure formation with CTAB as a surfactant than the SDBS. Moreover, the SEM microstructure results of double encapsulation using both TiO₂ and SiO₂ suggested thicker coating of particles when compared with single encapsulated counterparts. The cold phase of layered double encapsulation of OTCBDM + SiO₂/TiO₂ shows a darker color than the doped combination as obtained from the CIE Lab results. This feature suggested that an efficient encapsulation and chromatic transition are achieved in a layered combination of double encapsulation than in a doped combination. The DSC spectra indicated the increase in enthalpy at the heat cycle from 94.147 J/g for the SiO₂ microencapsulated OTCBDM sample compared to all other samples shows thermal energy storage behavior for outdoor building applications. The UV–Vis absorbance spectra show two distinct peaks at 470 and at 610 nm related to the OTCBDM. The single‐layer encapsulated organic thermochromic black dye material shows less absorbance compared to the plain organic thermochromic black dye material. The double encapsulated sample has the highest absorbance compared to all other samples suggesting the material having better retention of peaks at 470 and at 610 nm. The thermographic analysis (TGA) shows when compared to the plain and single encapsulated OTCBDM samples, the double encapsulated samples demonstrated higher thermal endurance characteristics due to thicker layer coatings of the shell over the core structure. The novelty of this work relies on the double encapsulation of OTCBDMs using SiO₂ and TiO₂ to improve the photodegradation behavior of the organic core dye particles, and we have demonstrated that the cationic surfactant CTAB outperforms than the SDBS in microencapsulation processes.

Thermochromic materials (TCMs) reversibly change their color or near‐infrared response with temperature, and a growing literature treats them as passive self‐regulating components in energy‐efficient buildings, wearable diagnostics, cold‐chain monitoring, and adaptive optical systems. Most existing reviews, however, are descriptive surveys that catalog mechanisms and processing routes without testing them against one another or against the realities of deployment. The present review takes a deliberately critical and comparative stance. Rather than an inventory of eight unconnected switching effects, the underlying physics is grouped into three families, namely, electronic and structural transitions in solids, molecular reconfiguration in discrete species, and supramolecular ordering in mesophases, and a common set of performance descriptors lets dissimilar materials be compared on an equal footing. The platforms are then assessed against those descriptors, with emphasis on the doping trade‐offs that govern the transition temperature of vanadium dioxide, the toxicity and regulation that render mercury‐based ionic conductors effectively unusable, and the photodegradation and cycling fatigue that constrain organic leuco‐dye and spiro systems. Synthesis, microencapsulation, and coating are treated as a single manufacturing chain and judged on scalability, reproducibility, cost, and technology readiness, since these factors, not laboratory optical contrast, ultimately decide whether a technology reaches the market. Durability is analyzed through combined ultraviolet, thermal, oxidative, and hydrolytic stress, and through the reproducibility gap left by nonstandard accelerated‐aging protocols. Deployment is framed within intelligent engineering systems, where TCMs act as passive actuators alongside sensor networks, building‐management systems, and digital‐twin models. The argument is supported by eight original schemes and eight comparative tables. We conclude that the principal barriers to adoption are no longer the questions of scientific novelty but of durability, cost at scale, standardization, and system‐level integration, and we map the research directions most likely to close these gaps.

Electric Vehicle drive systems must provide fast torque response, low or minimal torque ripple, robustness to both parameter variations and external disturbances. Permanent Magnet Synchronous Motors (PMSMs) are commonly found in electric vehicle propulsion applications due to their high power density, high efficiency, and excellent dynamic performance. However, performance degradation in torque control of PMSMs under time-varying conditions arises from the nonlinear characteristics of motors and their high sensitivity to changes in system parameters. This paper presents a torque-control method with high dynamic bandwidth that combines three techniques: (1) Nonlinear Sliding Mode Torque Control; (2) Predictive Current Control; and (3) Disturbance Estimation. The sliding mode controller provides improved robustness against uncertainties about the system. In addition, the predictive current control provides improved accuracy in current tracking and significantly reduces the time required to achieve a steady state. A disturbance observer is used to compensate for load disturbances and model errors in the motor model. The integrated control architecture is simulated and modeled in MATLAB/Simulink for a typical EV driving environment. The simulation framework produced faster and more accurate torque tracking than conventional PI-type vector controllers, as well as reduced torque ripple and improved disturbance rejection under similar operating conditions. The results demonstrate that the proposed method is a viable candidate for high-performance EV propulsion systems while acknowledging practical limitations such as chattering, tuning complexity, sampling time sensitivity, and the need for further experimental validation.