Search Results (11)

Multiplication is an arithmetic operation that has a significant impact on the performance of several real-life applications such as digital signals, image processing, and machine learning. The main concern of electronic system designers is energy optimization with minimal penalties in terms of speed and area for designing portable devices. In this work, a very-large-scale integration (VLSI) design and delay/area performance comparison of array, Wallace tree, and radix-4 Booth multipliers was performed. This study employs different word lengths, with an emphasis on the design of floating-point multipliers. All multiplier circuits were designed and synthesized using Alliance open-source tools in 350 nm process technology with the minimum delay constraint. The findings indicate that the array multiplier has the highest delay and area for all the multiplier sizes. The Wallace multiplier exhibited the lowest delay in the mantissa multiplication of single-precision floating-point numbers. However, no significant difference was observed when compared with the double-precision floating-point multipliers. The Wallace multiplier uses the lowest area in both the single- and double-precision floating-point multipliers. Full article

The Dual Carry Approximate Adder (DCAA) is proposed as an advanced 8-bit approximate adder featuring dual carry-out and carry-in full adders (FAs) along with an Error Reduction Unit (ERU) to enhance accuracy. The 8-bit adder is partitioned into upper and lower 4-bit blocks, connected via a dual carry-out full adder and a dual carry-in full adder. To minimize impact on the critical path, an ERU is designed for efficient error correction. Four variants of the DCAA are provided, allowing users to select the most suitable design based on their specific power, area, and accuracy requirements. The DCAA achieves a 78% reduction in Mean Error Distance (MED) while maintaining high computational speed and efficiency. When applied to Wallace Tree multipliers, it reduces delay by 32% compared to ripple carry adders (RCAs), and in in-memory computing (IMC) architectures, it significantly improves accuracy with minimal delay overhead. Experimental results demonstrate that the DCAA offers a well-balanced trade-off between accuracy, speed, and resource efficiency, making it suitable for high-performance, error-tolerant applications. Compared to existing approximate adders, DCAA exhibits superior error correction capabilities while achieving significantly lower delay. Furthermore, its efficient hardware implementation enables seamless integration into various computing paradigms, including AI accelerators and neuromorphic processors. Additionally, the scalability of the design allows for flexible adaptation to different bit-widths, making it a versatile solution for next-generation computing architectures. Full article

In the nano-scale era, enhancing speed while minimizing power consumption and area is a key objective in integrated circuits. This demand has motivated the development of approximate computing, particularly useful in error-tolerant applications such as multimedia, machine learning, signal processing, and scientific computing. In this research, we present a novel method to create approximate integer multiplier circuits. This work is based on a modification of the well-known Wallace tree multiplier, called the Reduced Complexity Wallace Multiplier (RCWM). Approximation is introduced by replacing conventional Full Adders with approximate ones during the partial product reduction phase. This research investigates the characteristics of 8×8-, 16×16-, and 32×32-bit Approximate Reduced Complexity Wallace Multipliers (ARCWM), evaluating their accuracy, area usage, delay, and power consumption. Given the vast search space created by different combinations and placements of these approximate Adders, a Genetic Algorithm was used to efficiently explore this space and optimize the ARCWMs. The resulting ARCWMs have an area reduction of up to 65% and a power consumption reduction of up to 70%, with no worse delay than the RCWM. Multipliers created with this method can be used in any application that requires parallel multiplication, such as neural accelerators, trading accuracy for area and power reduction. Additionally, an ARCWM can be used alongside a slow shift-and-accumulate multiplier trading off accuracy for faster calculation. This methodology provides valuable guidance for designers in selecting the optimal configuration of approximate Full Adders, tailored to the specific requirements of their applications. Alongside the methodology, we provide all of the tools used to achieve our results as open-source code, including the Register-Transfer Level (RTL) code of the 8×8-, 16×16-, and 32×32-bit Wallace Multipliers. Full article

In this paper, a multichannel FIR filter design based on the Time Division Multiplex (TDM) approach that incorporates one multiply and add unit, regardless of the variable coefficient length and varying channels, by associating the resource sharing doctrine is suggested. A multiplier based on approximate distributed arithmetic (DA) circuits is employed for effective resource optimization. Although no explicit multiplication was conducted in this realization, the radix-8 and radix-4 Booth algorithms are utilized in the DA framework to curtail and optimize the partial products (PPs). Furthermore, the input stream is truncated with an erratum mending unit to roughly construct the partial products. For an aggregation of PPs, an approximate Wallace tree is taken into consideration to further minimize hardware expenses. Consequently, the suggested design’s latency, utilized area, and power usage are largely reduced. The Xilinx Vertex device is expedited, given the synthesis of the suggested multichannel realization with 16 taps, which is simulated using the Verilog formulary. It is observed that the filter structure with one channel produced the desired results, and the system’s frequency can support up to 429 MHz with a reduced area. Utilizing TSMC 180 nm CMOS technology and the Cadence RC compiler, cell-level performance is also achieved. Full article

The partial substitution of chemical fertilizer with organic fertilizer is a crucial practice for enhancing crop production and quality, although its impact on natural rubber has rarely been explored. In this study, a two-year field experiment was conducted to investigate the impact of different nitrogen application rates and varying proportions of organic nitrogen substitution on dry rubber yield, nitrogen nutrition, and natural rubber properties. Regarding nitrogen application, the control treatment received no nitrogen amendment, while the low-nitrogen treatment was amended with 138 g·tree⁻¹·year⁻¹ of nitrogen. The medium-nitrogen treatment received 276 g·tree⁻¹·year⁻¹ of nitrogen, and the high-nitrogen treatment received 552 g·tree⁻¹·year⁻¹ of nitrogen. In addition, the low-organic-nitrogen substitution treatment and medium-organic-nitrogen substitution treatment were amended with 276 g·tree⁻¹·year⁻¹ of nitrogen each. The results demonstrated that the 50% organic nitrogen substitution treatment resulted in the highest dry rubber yield across all sampling periods, ranging from 46.43 to 94.65 g·tree⁻¹. Additionally, this treatment exhibited superior soil total nitrogen (1067.69 mg·kg⁻¹), available nitrogen (84.06 mg·kg⁻¹), and nitrogen content in roots (1.08%), leaves (3.25%), fresh rubber latex (0.27%), and raw natural rubber (0.44%) compared with other treatments. In terms of the physical properties of natural rubber, the 50% organic nitrogen substitution treatment resulted in advantages in the weight-average molecular weight (1.57 × 10⁶ g·mol⁻¹), number-average molecular weight (0.36 × 10⁶ g·mol⁻¹), plasticity retention index (97.35%), Wallace plasticity (40.25), and Mooney viscosity (81.40). For mechanical properties, natural rubber from the substitution treatment exhibited higher tensile strength (19.84 MPa), greater elongation at break (834.75%), and increased tear strength (31.07 N·mm⁻¹). Overall, the substitution of 50% chemical nitrogen fertilizer with organic nitrogen fertilizer improved nitrogen nutrition in rubber trees by introducing organic nitrogen input, resulting in remarkable enhancements in natural rubber properties. Therefore, the incorporation of organic fertilizer as a substitution for 50% of chemical fertilizer is demonstrated as an effective strategy for improving both the yield and properties of natural rubber. Full article

It is a difficult undertaking to reliably estimate global terrestrial evapotranspiration (ET) using the Visible Infrared Imaging Radiometer Suite (VIIRS) at high spatial and temporal scales. We employ deep neural networks (DNN) to enhance the estimation of terrestrial ET on a global scale using satellite data. We accomplish this by merging five algorithms that are process-based and that make use of VIIRS data. These include the Shuttleworth–Wallace dual-source ET method (SW), the Priestley–Taylor-based ET algorithm (PT-JPL), the MOD16 ET product algorithm (MOD16), the modified satellite-based Priestley–Taylor ET algorithm (MS-PT), and the simple hybrid ET algorithm (SIM). We used 278 eddy covariance (EC) tower sites from 2012 to 2022 to validate the DNN approach, comparing it to Bayesian model averaging (BMA), gradient boosting regression tree (GBRT) and random forest (RF). The validation results demonstrate that the DNN significantly improves the accuracy of daily ET estimates when compared to three other merging methods, resulting in the highest average determination coefficients (R², 0.71), RMSE (21.9 W/m²) and Kling–Gupta efficiency (KGE, 0.83). Utilizing the DNN, we generated a VIIRS ET product with a 500 m spatial resolution for the years 2012–2020. The DNN method serves as a foundational approach in the development of a sustained and comprehensive global terrestrial ET dataset. The basis for characterizing and analyzing global hydrological dynamics and carbon cycling is provided by this dataset. Full article

Accurate prediction of orchard evapotranspiration (ET) can optimize orchard water management. Based on the jujube (Zizyphus jujuba), ET was continuously measured from 2016 to 2019 using a large weighing lysimeter; the actual jujube ET was compared with the ET simulated with the Priestley–Taylor (P–T), Dual Crop Coefficient (Dual Kc), and Shuttleworth–Wallace (S–W) models, to verify the accuracy of the three models. The results showed that, from 2016 to 2019, the whole growth period of jujube ET was 532–592 mm and the crop coefficient was 0.85–0.93. The basal crop coefficients of the calibrated Dual Kc model were 0.4, 1.0, and 0.5 at the initial, middle, and ending growth stages, respectively. The overall simulation error of the Dual Kc model was low, and simulations were stable during the four years of the study. However, because of rough estimation the water stress coefficient (K_s) simulation accuracy will be reduced in the case of serious water shortage. The simulation error of the S–W model was greater than the simulation error of the Dual K_c model, and the simulations were unstable and vulnerable to interannual changes. The simulation error of the traditional P–T model was large. When the parameter “α” solution method was improved, the simulation accuracy was significantly improved, and the P–T model’s simulation accuracy was only slightly lower than that of the Dual Kc model. However, the model was easily affected by changes in net radiation and air temperature. Therefore, the Dual Kc model is recommended for estimating the ET of young jujube trees in arid areas. Full article

Nowadays, Finite Impulse Response (FIR) filters are used to change the attributes of a signal in the time or frequency domain. Among FIR filters, a reconfigurable filter has the advantage of changing the coefficient in real-time, while performing the operation. In this paper, the Anti-Symmetric Product Coding (APC) and Odd Multiple Storage (OMS) modules are utilized to implement the reconfigurable FIR filter (RFIR–APC–OMS). Herein, the APC–OMS module is used to reduce the area of the RFIR architecture. The performance of the RFIR–APC–OMS is analyzed in terms of: area, power, delay, LUT, flip flop, slices, and frequency. RFIR–APC–OMS has reduced 3.44% of area compared to the existing RFIR architecture employing the Dynamic Reconfigurable Partial Product Generator (DRPPG) module. Full article

The data movement between the processing and storage units has been one of the most critical issues in modern computer systems. The emerging Resistive Random Access Memory (RRAM) technology has drawn tremendous attention due to its non-volatile ability and the potential in computation application. These properties make them a perfect choice for application in modern computing systems. In this paper, an 8-bit radix-4 non-volatile parallel multiplier is proposed, with improved computational capabilities. The corresponding booth encoding scheme, read-out circuit, simplified Wallace tree, and Manchester carry chain are presented, which help to short the delay of the proposed multiplier. While the presence of RRAM save computational time and overall power as multiplicand is stored beforehand. The area of the proposed non-volatile multiplier is reduced with improved computing speed. The proposed multiplier has an area of 785.2 $\mathsf{\mu }$m${}^2$ with Generic Processing Design Kit 45 nm process. The simulation results show that the proposed multiplier structure has a low computing power at 161.19 $\mathsf{\mu }$W and a short delay of 0.83 ns with 1.2 V supply voltage. Comparative analyses are performed to demonstrate the effectiveness of the proposed multiplier design. Compared with conventional booth multipliers, the proposed multiplier structure reduces the energy and delay by more than 70% and 19%, respectively. Full article

From 1992 to 2009, 334 trees were sampled by insecticidal knockdown on Borneo, Malaysia. Here, we describe the taxonomic composition of the 9671 specimens and 1589 species Curculionoidea collected (with additional notes on Cerambycidae). We found a largely unknown fauna with an assumed proportion of over 80% of species new to science, including all 33 Apionidae and 26 Ceutorhynchinae species. Specialists could usually identify only a few specimens leaving the remaining beetles for further investigation. The samples contain numerous genera, two tribes (Egriini, Viticiini), one subfamily (Mesoptiliinae) and one family (Belidae) new to Borneo and several genera not recorded west of the Wallace line before. These data show how little is known about canopy diversity. The lack of taxonomic knowledge implies a respective lack of autecological knowledge and is alarming. Some taxa differed conspicuously between primary and disturbed forests. In contrast to common literature, our results let us conclude that current efforts to narrow down the extent of tropical diversity and its ecological importance must consider the enormous species diversity of the canopy. Full article

A study was carried out to evaluate the potential use of the two-source Shuttleworth and Wallace (SW) model to compute the intra-orchard spatial variability of actual evapotranspiration (ET) of olive trees using satellite images and ground-based climate data. The study was conducted in a drip-irrigated olive orchard using satellite images (Landsat 7 ETM+), which were acquired on clear sky days during the main phenological stages (2009/10 growing season). The performance of the SW model was evaluated using instantaneous latent heat flux (LE) measurements that were obtained from an eddy correlation system. At the time of satellite overpass, the estimated values of net radiation ( ${\mathrm{Rn}}_{\mathrm{i}}$ ) and soil heat flux ( ${\mathrm{G}}_{\mathrm{i}}$ ) were compared with ground measurements from a four-way net radiometer and soil heat flux plates, respectively. The results indicated that the SW model subestimated instantaneous LE (W m⁻²) and daily ET (mm d⁻¹), with errors of 12% and 10% of observed values, respectively. The root mean square error (RMSE) and mean absolute error (MAE) values for instantaneous LE were 26 and 20 W m⁻², while those for daily values of ET were 0.31 and 0.28 mm d⁻¹, respectively. Finally, the submodels computed ${\mathrm{Rn}}_{\mathrm{i}}$ and ${\mathrm{G}}_{\mathrm{i}}$ with errors of between 4.0% and 8.0% of measured values and with RMSE and MAE between 25 and 39 W m⁻². Full article