Long-term Reliability Research Articles

High Stability of Broadband Photomultiplier Organic Photodetector with metal ion-chelated polymer as an electron tunneling injection dipole layer

Broadband photomultiplier organic photodetectors (PM-OPDs) have tremendous potential for use in a variety of photoimaging, physical health monitoring, and wearable applications. However, the interfacial mismatch between electrodes and organic semiconductors inhibits the long-term working stability and reliability of devices. Here, we devised high-performance and stability PM-OPDs by using Zn2+-chelated ethoxylated-polyethylenimine (denoted as PEIE-Zn) as an electron tunneling injection dipole layer between ITO and P3HT:PC71BM: Y6 (3:20:80) broadband photoactive layer. The specific detectivity of the PEIE-Zn-modified PM-OPDs was higher than 1012 Jones in the whole spectral response range (350–1000 nm) under 10V bias. The external quantum efficiency of the device exceeded 1000 % in the whole spectral response range under −20V bias. The transient photoresponse curve of the device has no obvious peaks and fluctuations, and the photocurrent density drops only 2.34 % and 0.25 % at 10 V and −20 V bias after illumination, respectively. The device exhibited very good stability over the course of a week, with its photocurrent density maintained at more than 98.94 % of the initial photocurrent density in the ambient environment without encapsulation. This work improves interface contact by modifying the ITO electrode with PEIE-Zn, providing a practical design solution for devices with high response and stability for broadband PM-OPDs.

Laser-Assisted Structuring of Graphene Films with Biocompatible Liquid Crystal Polymer for Skin/Brain-Interfaced Electrodes.

The work presented here introduces a facile strategy for the development of flexible and stretchable electrodes that harness the robust characteristics of carbon nanomaterials through laser processing techniques on a liquid crystal polymer (LCP) film. By utilizing LCP film as a biocompatible electronic substrate, control is demonstrated over the laser irradiation parameters to achieve efficient pattern generation and transfer printing processes, thereby yielding highly conductive laser-induced graphene (LIG) bioelectrodes. To enhance the resolution of the patterned LIG film, shadow masks are employed during laser scanning on the LCP film surface. This approach is compatible with surface-mounted device integration, enabling the circuit writing of LIG/LCP materials in a flexible format. Moreover, kirigami-inspired on-skin bioelectrodes are introduced that exhibit reasonable stretchability, enabling independent connections to healthcare hardware platforms for electrocardiogram (ECG) and electromyography (EMG) measurements. Additionally, a brain-interfaced LIG microelectrode array is proposed that combines mechanically compliant architectures with LCP encapsulation for stimulation and recording purposes, leveraging their advantageous structural features and superior electrochemical properties. This developed approach offers a cost-effective and scalable route for producing patterned arrays of laser-converted graphene as bioelectrodes. These bioelectrodes serve as ideal circuit-enabled flexible substrates with long-term reliability in the ionic environment of the human body.

The political economy of electricity system resource adequacy and renewable energy integration: A comparative study of Britain, Italy and California

The need to integrate growing shares of variable renewable resources, like solar and wind, into the power system has initiated a new wave of resource adequacy policy reforms. Securing adequate resources on the system, particularly flexible and peak capacity, is indeed crucial for ensuring long-term grid reliability amid increased supply variability. While extensively explored from a techno-economic perspective, the political economy drivers and implications of these changes are frequently overlooked. Yet, power system evolution is not merely shaped by logics of techno-economic optimisation, it is also inherently political, rooted in specific liberalisation histories, political and institutional settings.This paper contributes to the literature by conducting a comparative political economy analysis of recent resource adequacy reforms in Britain, Italy, and California. It explores how differences in the technical and political economy contexts of these jurisdictions affected their strategies for securing resource adequacy capacity and investment between 2013 and 2021. Conclusions draw on the analysis of over 134 policy documents and 53 in-depth interviews with power system stakeholders.All jurisdictions introduced significant changes in resource adequacy policy, including explicit out-of-market mechanisms to remunerate resource adequacy capacity. The energy transition is thus reconfiguring state-market relations in the power sector, even in traditionally liberal countries. However, variation exists in the scope of reform, mechanism designs, policy trade-offs, and technological outcomes. This stems from context-specific political priorities, state-market relations, national and multi-level governance arrangements, market structures and stakeholder interests. This has important implications for power sector governance, as discussed in this paper.

Enhancing electrochromic supercapacitor electrode performance through different donor compartments in D-A-D type conjugated polymers

Conjugated polymers (CPs), particularly donor-acceptor-donor (D-AD) type polymers, have emerged as promising materials as supercapacitor electrode. In this study, 3-hexylthiophene and ethylenedioxythiophene (EDOT) as donor compartments in D-A-D type CPs, with an indenoquinoxalinone-based acceptor, were investigated for supercapacitor electrode performance. Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and UV–Vis spectroscopy were employed to analyze the chemical structures and optical properties of the monomers, respectively. For surface characterization of the polymers, scanning electron microscope (SEM) and Brunauer-Emmett-Teller (BET) analysis were used. Electrochromic behaviors were investigated via spectroelectrochemistry and kinetic studies. The electrochemical performance of the polymers was evaluated through cyclic voltammetry, galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) measurements. The specific capacitance, energy density, and power density of the polymers were compared. Results showed that they were promising electrochromic material for supercapacitor application due to their high specific capacitance. Since EDOT containing polymer exhibited enhanced electrochemical properties, it was used to construct supercapacitor. Besides cyclic voltammetry and GCD characterization of device, the electrochemical cycling performance of it was assessed to evaluate the long-term reliability of the polymer as supercapacitor electrode material. This study provides valuable insights into the role of donor compartments, specifically 3-hexylthiophene and EDOT in D-A-D type CPs. The findings also highlight the potential of the indenoquinoxalinone-based acceptors in electrochromic supercapacitors. The results contribute to the design and development of enhanced supercapacitor materials with improved energy storage capabilities, offering new possibilities for utilizing D-A-D type polymers with indenoquinoxalinone-based acceptors.

Broadband Port-Selective Silicon Beam Scanning Device for Free-Space Optical Communication

Indoor free space optical (FSO) communication technology that provides high-speed connectivity to edge users is expected to be introduced in the near future mobile communication system, where the silicon photonics solid-state beam scanning device is a promising tool because of its low cost, long-term reliability, and other beneficial properties. However, the current two-dimensional beam scanning devices using grating coupler arrays have difficulty in increasing the transmission capacity because of bandwidth regulation. To solve the problem, we have introduced a broadband surface optical coupler, “elephant coupler,” which has great potential for combining wavelength and spatial division multiplexing technologies into the beam scanning device, as an alternative to grating couplers. The prototype port-selective silicon beam scanning device fabricated using a 300 mm CMOS pilot line achieved broadband optical beam emission with a 1 dB-loss bandwidth of 40 nm and demonstrated beam scanning using an imaging lens. The device has also exhibited free-space signal transmission of non-return-to-zero on-off-keying signals at 10 Gbps over a wide wavelength range of 60 nm. In this paper, we present an overview of the developed beam scanning device. Furthermore, the theoretical design guidelines for indoor mobile FSO communication are discussed.

In-Circuit Assessment of the Long-Term Reliability of E-Mode GaN HEMTs

In-Circuit Assessment of the Long-Term Reliability of E-Mode GaN HEMTs

Analyzing long-term reliability and potential of organic eutectic Phase Change Material as thermal batteries

The current century is experiencing a notable and expeditious transition toward environmentally sustainable and renewable energy sources to mitigate the effects of climate change. Solar energy is a widely utilized renewable energy source due to its abundance and cleanliness despite its disparate distribution. Integrating Latent Heat Energy Storage (LHES) components into solar energy storage systems can potentially mitigate anomalies in solar radiation. Phase Change Materials (PCMs) are widely regarded as the most commonly utilized substance for Thermal Energy Storage (TES). The thermal management potential of a TES system is substantially hindered due to the limited thermal conductivity of PCMs. The present study attempts to create a binary eutectic PCM for employment in desalination systems, electronic thermal management, and other medium-temperature applications. The melt blending approach was used to synthesize a Binary Eutectic PCM (BEPCM), mixing paraffin and palmitic acid, and the composite's thermophysical properties were evaluated. The stability of BEPCM was confirmed by using the techniques of Thermogravimetric Analysis and Fourier Transform Infrared Spectroscopy. The synthesized BEPCM's thermal conductivity was 0.256 W⸱m−1⸱K−1 (an increase of 11.3 % above palmitic acid). The melting point and latent heat values were found to be 55 °C and 160 J/g. An in-depth morphological and thermophysical analysis following 4000 thermal cycles validated the EPCM's long-term reliability. Thus, a cost-effective, robust, and reliable PW-PA-based BEPCM was manufactured. The composite benefits TES systems operating at moderate temperatures due to their improved thermophysical capabilities.

Study of 100V GaN power devices in dynamic condition and GaN RF device performances in sub-6GHz frequencies

AlGaN/GaN devices for both power and RF applications have been investigated in this work. In particular, regarding power applications, 100 V p-GaN gate transistors have been analysed both in DC and in dynamic conditions with specific attention to the high temperature behaviour.As a first step, the high temperature behaviour of the on-resistance (RON) of a reference process (STD process) has been investigated. The role of the different resistive components of the transistor has been analysed by evaluating how their relative weight changes with the temperature increase. Then, two different p-GaN process variations (process A and process B) have been proposed and compared to the STD process to show their improvement in terms of a limited RON increase at 150 °C, highlighting the relevance of an improved p-GaN gate processing.Secondly, the temperature effect on the RON-degradation induced by off-state drain voltage stress has been investigated in process B-like devices. The impact of temperature on the time required to reach a steady state degradation has been addressed, enabling the comparison of the RON degradation (RON/ RON0) at equilibrium. Tests performed on several samples have demonstrated the invariance of the RON/ RON0 ratio in the 25 °C to 150 °C range, suggesting the possibility to reduce the measurements required for dynamic-RON evaluation at different T.Finally, RF devices (featuring Schottky metal gate) have been characterized in terms of DC/RF performances and long-term reliability (through HTRB tests). Different trials with increasing aluminium content of the AlGaN barrier have been compared, showing the correlation with the maximum saturation current and the output power. Moreover, the trade-off with reliability specifications has been put in evidence.

Transient liquid phase bonding using Cu foam and Cu–Sn paste for high-temperature applications

This study presents a new structure for transient liquid phase (TLP) bonding using Cu foam and Cu–Sn paste. Cu foam and Cu–Sn paste with large reaction surface areas were used to reduce the long bonding time, which is a disadvantage of the conventional TLP bonding process. After applying the Cu–Sn paste at an optimized ratio to the top and bottom of the Cu foam, pressure was applied to fill the pores inside the Cu foam with the paste, and a bonding process was performed at 260 °C under a pressure of 3 kgf. Bonded joints composed of only the Cu skeleton and Cu–Sn intermetallic compounds (IMCs) were confirmed within a bonding time of 5 min. In addition, the proportion of the Cu3Sn phase in the joint increased with the bonding time. After a bonding time of 40 min, the joint was mostly composed of a Cu skeleton and Cu3Sn, with a measured shear strength of approximately 39.2 MPa. After the joint analysis of the as-bonded samples, a high-temperature storage test (HTST) was conducted to evaluate their high-temperature long-term reliability. As a result of HTST, because most of the joint was converted to Cu3Sn after the bonding process, the shear strength did not decrease despite heat treatment at a high temperature of 240 °C, and a similar microstructure of the joint was maintained.

C1 Transposterior Arch Lateral Mass Screws Combined With C2 Pedicle Screw and Rod Fixation for Pediatric Atlantoaxial Subluxation: A Minimal 10-Year Follow-up Outcome Analysis.

Although the short-term outcomes of the 1-step reduction and fixation technique using C1 transposterior arch lateral mass screws combined with C2 pedicle screw and rod fixation system for the treatment of pediatric atlantoaxial subluxation (AAS) have been satisfactory, its long-term outcomes and impact on spinal development are not well studied. This study was intended to assess the long-term reliability of this technique for pediatric AAS. A retrospective case series study was conducted to analyze the minimum 10-year follow-up outcomes from 7 pediatric patients with AAS who underwent atlantoaxial fusion using the aforementioned technique. Quality of life and cervical range of motion were both measured thoroughly. In addition, vertical growth within the fusion construct (C1-2), overall cervical alignment, and subaxial cervical spine degeneration were evaluated radiographically. The mean age of the 7 patients was 8.14 ± 2.41 (6-12) years at the time of surgery. The mean follow-up period was 11.00 ± 1.15 (10-13) years. No patients presented identifiable intervertebral disk degeneration or segmental instability in the subaxial cervical spine except for 1 patient who showed mild intervertebral disk degeneration. Vertical growth did continue within the atlantoaxial complex after surgery (11.90% ± 2.37%); however, there was a decrease in the percentage of vertical growth compared with the corresponding normal populations of the same age and sex. Moreover, there was a significant decrease in the range of cervical extension and rotation motion, and the overall cervical alignment straightened at the latest follow-up. The 1-step reduction and fixation technique is a relatively reliable surgical technique for pediatric AAS, which does not adversely affect the postoperative quality of life or the subaxial cervical degeneration. Nevertheless, certain limitations, such as decreased cervical range of motion and changes in cervical alignment, should be concerned.

Temperature Reliability Investigation for a 400 W Solid-State Power Amplifier under High and Cold Conditions

In order to study the temperature reliability of high-power amplifiers under high cand cold conditions, a 400 W solid-state power amplifier was taken as an example to explore the variation in its performance. The test results showed that its output power, gain, and power-added efficiency increased with the increase in temperature at a fixed frequency. Under a fixed input power, Pout and gain both showed different trends with the rising temperature. Within the frequency band of 2–10 MHz, the higher the temperature, the better the output power and gain. However, within the frequency range of 10–30 MHz, the higher the temperature, the worse the performance. Moreover, with the increasing temperature, its power-added efficiency, the second harmonic and the third harmonic also showed a decreasing trend. Detailed analysis showed that the degradation and inversion of performance parameters are closely related to the zero temperature coefficient and self-heating effect of the lateral double-diffused metal–oxide–semiconductor field-effect transistor. Meanwhile, it is also affected by the circuit structure and thermal design of the PA. In order to ensure stable performance in different environments, performance degradation can be improved by hardware compensation. Therefore, analyzing the working parameters at different temperatures for high-power PAs is the key to achieving temperature control and ensuring their long-term stability and reliability. This can provide relatively accurate reference data for subsequent heat dissipation optimization, greatly improve design efficiency, and even shorten the development cycle and reduce costs.

A Roadmap from Functional Materials to Plant Health Monitoring (PHM).

Soft bioelectronics have great potential for the early diagnosis of plant diseases and the mitigation of adverse outcomes such as reduced crop yields and stunted growth. Over the past decade, bioelectronic interfaces have evolved into miniaturized conformal electronic devices that integrate flexible monitoring systems with advanced electronic functionality. This development is largely attributable to advances in materials science, and micro/nanofabrication technology. The approach uses the mechanical and electronic properties of functional materials (polymer substrates and sensing elements) to create interfaces for plant monitoring. In addition to ensuring biocompatibility, several other factors need to be considered when developing these interfaces. These include the choice of materials, fabrication techniques, precision, electrical performance, and mechanical stability. In this review, some of the benefits plants can derive from several of the materials used to develop soft bioelectronic interfaces are discussed. The article describes how they can be used to create biocompatible monitoring devices that can enhance plant growth and health. Evaluation of these devices also takes into account features that ensure their long-term durability, sensitivity, and reliability. This article concludes with a discussion of the development of reliable soft bioelectronic systems for plants, which has the potential to advance the field of bioelectronics.

Lifetime estimation of thin-film transistors in organic emitting diode display panels with compensation

Oxide semiconductor thin-film transistors (TFTs) are used in the pixel array and gate driver circuits of organic light emitting diode (OLED) display panels. Long-term reliability characteristics of the TFTs are a barometer of the lifetime of OLED display panels. The long-term reliability of the driver TFTs is evaluated in a short time under high voltages and high temperature for an accelerated degradation test. If reliability parameters from the power law or stretched-exponential functions are the same for individual devices and devices in an operating panel, the lifetime of the panel can be accurately estimated. However, since compensation circuits are designed into operating panels, an environmental discrepancy exists between the accelerated test of single devices and the operation of devices in the panel. Herein, we propose a novel compensation stretched-exponential function (CSEF) model which captures the effect of the threshold voltage compensation circuit in the panel. The CSEF model not only bridges the discrepancy between individual devices and panel devices, but also provides a method to accurately and efficiently estimate the long-term lifetime of all display panels that utilize compensation circuits.

3D Printed and Embedded Strain Sensors in Structural Composites for Loading Monitoring and Damage Diagnostics

The development of novel embedded sensors for structural health monitoring (SHM) is crucial to provide real-time assessments of composite structures, ensuring safety, and prolonging their service life. Early damage diagnostics through advanced sensors can lead to timely maintenance, reducing costs and preventing potential catastrophic failures. This paper presents the synthesis, 3D printing, and characterization of novel embedded strain sensors using multi-walled carbon nanotube (MWCNT) -enhanced nanocomposites in fiberglass reinforced composites for potential damage diagnostics and SHM applications. MWCNTs are dispersed within structural epoxy for the additive manufacturing of nanocomposites with piezoresistive sensing capability. The 3D-printed nanocomposite sensors are embedded in fiberglass-reinforced composite laminates. The piezoresistive sensing capabilities of the 3D-printed sensors within composites are characterized by applying different levels of maximum loads and load rates under three-point bending loads. Additionally, the long-term reliability of the developed strain sensors is evaluated up to 1000 cycles. The recorded piezoresistive sensing signals show high sensitivity for the externally applied bending loads with advanced gauge factor up to 100, resulting in potential load sensing capability for in-situ damage diagnostics and real-time SHM for structural composites.

Temperature-Immune, Wide-Range Flexible Robust Pressure Sensors for Harsh Environments.

Flexible pressure sensors possess vast potential for various applications such as new energy batteries, aerospace engines, and rescue robots owing to their exceptional flexibility and adaptability. However, the existing sensors face significant challenges in maintaining long-term reliability and environmental resilience when operating in harsh environments with variable temperatures and high pressures (∼MPa), mainly due to possible mechanical mismatch and structural instability. Here, we propose a composite scheme for a flexible piezoresistive pressure sensor to improve its robustness by utilizing material design of near-zero temperature coefficient of resistance (TCR), radial gradient pressure-dividing microstructure, and flexible interface bonding process. The sensing layer comprising multiwalled carbon nanotubes (MWCNTs), graphite (GP), and thermoplastic polyurethane (TPU) was optimized to achieve a near-zero temperature coefficient of resistance over a temperature range of 25-70 °C, while the radial gradient microstructure layout based on pressure division increases the range of pressure up to 2 MPa. Furthermore, a flexible interface bonding process introduces a self-soluble transition layer by direct-writing TPU bonding solution at the bonding interface, which enables the sensor to achieve signal fluctuations as low as 0.6% and a high interface strength of up to 1200 kPa. Moreover, it has been further validated for its capability of monitoring the physiological signals of athletes as well as the long-term reliable environmental resilience of the expansion pressure of the power cell. This work demonstrates that the proposed scheme sheds new light on the design of robust pressure sensors for harsh environments.

A Comparative Study of Eggshell and Commercial Sorbent-Based Catalysts through Synthesis and Characterization for SESR Process

Hydrogen is a clean and valuable energy carrier, and there is growing consensus that a hydrogen-based economy could be the key to ensuring the long-term reliability and environmental friendliness of the world’s energy supply. There are a variety of methods and technologies that may be used to produce hydrogen; among them, sorption-enhanced steam reforming is regarded as the way that is the most effective. For the purpose of making a decision about which catalysts to employ in SESR in the future, this study compared three distinct kinds of catalysts. The wet impregnation method was used to manufacture the waste-derived CaO-implemented Ni-based catalysts, which were then used in sorption-enhanced steam reforming (SESR) to produce hydrogen (H2). X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analyses (TGA) were used to analyze the catalysts. XRD results showed that the crystallinity behavior for all types of catalysts such as 10NMA, 10NCMA-E, and 10NCMA was identical. The spinel compounds such as NiAl2O4 and MgAl2O4 were identified in all three types of catalysts. At high temperatures, such as at 800 °C, all catalysts were stable, evident from TGA results. During three sorption cycles, the 10NCMA-based catalyst demonstrated the highest sorption capacity among the three varieties of catalysts, followed by the 10NCMA-E catalyst. During the first, second, and third calcination cycles, the 10NCMA-based catalyst released 23.88%, 22.05%, and 23.33% CO2, respectively. 10NCMA-E can be a potential catalyst for the SESR process by decreasing the material manufacturing cost and overall cost of the SESR process.

The beneficial effect of Fe addition in PbTe-Ni diffusion bonded thermoelectric contact interfaces – A comprehensive phase evolution study

The development of reliable interconnects in thermoelectric (TE) modules is essential for the durability and serviceability of these solid-state devices. PbTe-based devices are used in mid-temperature range applications, with Ni being the most preferred interconnect. Ni reacts with PbTe to form a binary intermetallic, Ni3Te2 (β2). The sustained growth of this phase at higher service temperatures is adversarial to the long-term reliability of interconnects. This paper reports and discusses the beneficiary role of minor Fe-addition in the Ni contact alloy to arrest such unwarranted chemical interaction while ensuring proper bonding. PbTe and Ni-Fe (Fe = 1 at.%, 5 at.%) discs are diffusion bonded at 700 °C for various holding times. The current investigation leads to three noteworthy observations: 1) the formation of Fe-enriched Ni-Fe phase islands at the interface at microscale (1 - 10 µm), (2) Fe-segregation at the local interfaces (∼ 10 nm), and (3) the growth of a Ni-rich metastable Ni3-xTe phase, not present in Ni-Te binary phase diagram. Detailed examinations of these phenomena and crystallographic relations (β2 and Ni3-xTe) are conducted through advanced analytical TEM/STEM techniques. Furthermore, the PbTe-Ni reaction formulation is modified to accommodate such a Fe-enrichment phenomenon and is validated through free energy calculations.

Long-term reliability of photovoltaic c-Si modules – A detailed assessment based on the first Italian BIPV project

Assessing the long-term reliability of PV systems is important for understanding their energy and cost efficiency. Typically, estimates and predictions are based on indoor tests and accelerated ageing. However, fluctuating and differently interacting outdoor factors such as solar radiation, dust, and shadowing in real environment can impact the actual performance. This paper examines alterations related to ageing of c-Si PV modules, firstly by classifying the main factors that affect aged c-Si PV modules and then assessing the impact on their performance degradation by analysing a pilot BIPV system at Politecnico di Milano after 20 years of actual operation. Such system, which is highly representative since is the first public BIPV plant funded in Italy, was carefully and continuously monitored during its operating life. In particular, according to the visual/IR inspection carried out after the 20th year of operation, the main observed alteration in the modules were discoloration of the encapsulant, delamination, and chalking of the backsheet. The I-V characterization shown that all sampled modules had an overall degradation rate of less than 20 %, which is within the warranty limit, although in many cases the degradation rate over time shows a non-linear trend. Only one module experienced a severe fault that caused the complete loss of functionality. Obtained results confirm the reliability of c-Si technology, stressing the importance of a careful monitoring especially after the 15th year, when an increase of the degradation rate might occur.

Convolution Neural Networks for Motion Detection with Electrospun Reversibly-Cross-linkable Polymers and Encapsulated Ag Nanowires.

This paper presents the design, fabrication, and implementation of a novel composite film, a polybutadiene-based urethane (PBU)/AgNW/PBU sensor (PAPS), demonstrating remarkable mechanical stability and precision in motion detection. The sensor capitalizes on the integration of Ag nanowire (AgNW) electrodes into a neutral plane, embedded within a reversibly cross-linkable PBU polymer. The meticulous arrangement confers pore-free and interfaceless sensor formation, resulting in an enhanced mechanical robustness, reproducibility, and long-term reliability. The PBU polymer is subjected to an electrospinning process, followed by sequential Diels-Alder (DA) and retro-DA reactions to produce a planarized encapsulation layer. This pioneering technology, based on electrospinning, allows for more flawless engineering of the neutral plane as compared to conventional film lamination or layer-by-layer spin-coating processes. This encapsulation, matching the thickness of the preformed PBU film, effectively houses the AgNW electrodes. The PAPS outperforms conventional AgNW/PBU sensors (APS) in terms of mechanical stability and bending insensitivity. When affixed to various body parts, the PAPS generates distinctive signal curves, reflecting the specific body part and degree of motion involved. The PAPS sensor's utility is further magnified by the application of machine learning and deep learning algorithms for signal interpretation. K-means clustering algorithm authenticated the superior reproducibility and consistency of the signals derived from the PAPS over the APS. Deep learning algorithms, including a singular 1D convolutional neural network (1D CNN), long short-term memory (LSTM) network, and dual-layered combinations of 1D CNN + LSTM and LSTM + 1D CNN, were deployed for signal classification. The singular 1D CNN model displayed a classification accuracy exceeding 98%. The PAPS sensor signifies a pivotal development in the field of intelligent motion sensors.

Air source assisted ground source composite heat pump system: life cycle carbon emissions and simulation analysis

ABSTRACT Air source assisted ground source composite heat pump (DSHP) system is a combination of ground source heat pump (GSHP) and air source heat pump (ASHP) that makes use of both underground and outdoor temperatures to ensure long-term stability and reliability. The development of a carbon emission model for DSHP system involved a life-cycle assessment (LCA). This model was used to analyze the energy savings of DSHP in two different areas of China Nanjing and Hohhot. In both cases, an office building with an area of 3040 m2 was used as the subject of the study. The evaluation of energy savings using TRNSYS dynamic simulations revealed that the operation stage accounts for about 75%-85% of the carbon emission in the entire life cycle assessment of DSHP systems, Among them, refrigerant leakage produces a carbon footprint of more than 20%. The installation stage accounts for about 10% of the emissions, while the adjustment of the power energy structure during operation is crucial in achieving energy savings and emission reductions. A comparison study shows that DSHP can lower emissions by up to 23% when compared to traditional air conditioning systems like gas boiler and chiller system (BLR-CH). The use of DSHP is therefore a highly effective alternative for organizations committed to reducing their carbon footprint.