Projection Method Research Articles

Geographical origin identification of cinnamon using HPLC-DAD fingerprints and chemometrics

The commercial value of cinnamon depends largely on its geographical origin. This study proposed high-performance liquid chromatography-diode array detection (HPLC-DAD) fingerprints combined with chemometrics to identify geographical origins of cinnamons. Alternating trilinear decomposition (ATLD) algorithm was applied to extract meaningful chemical information from the HPLC fingerprint data. Then, non-targeted HPLC fingerprints and chemical component information were used as chemical descriptors to distinguish geographical origins using principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA)/N-way partial least squares-discriminant analysis (NPLS-DA). Satisfactory classification results were acquired for each discriminant model and the correct classification rates (CCRs) of training and test sets were 100%. Moreover, four characteristic variables were screened by variable importance in projection (VIP) method, three of which were reasonably identified as cinnamic acid, cinnamaldehyde and 2-methoxycinnamaldehyde, which can be regarded as potential markers to distinguish cinnamon from different geographical origins. The results indicated that HPLC-DAD fingerprints combined with chemometrics can be a promising means to identify the geographical origins and screen potential markers of cinnamon samples, especially in the absence of high-cost and sophisticated analytical instrumentals (e.g., high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy). This work can help to prevent cinnamon fraud practices and maintain the normal order of the cinnamon market.

Geometrical Penrose tilings are characterized by their 1-atlas

Penrose rhombus tilings are tilings of the plane by two decorated rhombi such that the decorations match at the junction between two tiles (like in a jigsaw puzzle). In dynamical terms, they form a tiling space of finite type. If we remove the decorations, we get, by definition, a sofic tiling space that we here call geometrical Penrose tilings. Here, we show how to compute the patterns of a given size which appear in these tilings by three different methods: two based on the substitutive structure of the Penrose tilings and the last on their definition by the cut and projection method. We use this to prove that the geometrical Penrose tilings are characterized by a small set of patterns called vertex-atlas, i.e., they form a tiling space of finite type. Though considered as folklore, no complete proof of this result has been published, to our knowledge.

Government size and the effectiveness of fiscal policy: the bigger the better?

Abstract This study investigates the effect of government size, as measured by the tax revenue to gross domestic product (tax-GDP) ratio, on output responses to increases in government purchases. First, we show that in a standard static neoclassical model, the stimulus effect of fiscal expansion on output increases with the tax-GDP ratio. This finding is quantitatively confirmed using a dynamic neoclassical model with standard functional forms and parameter values. To empirically test the theoretical findings, we analyze the responses of macroeconomic variables to an unanticipated increase in government purchases for 12 Organisation for Economic Cooperation and Development (OECD) countries during 1985–2019 using a state-dependent local projection method. The estimation results reveal that while output responses to an unanticipated fiscal expansion are significantly positive when the tax-GDP ratio is high, they are statistically indistinguishable from zero when the ratio is low. Overall, our findings suggest that fiscal expansion can stimulate output more effectively at high tax rates, unlike the well-known predictions of the traditional Keynesian model.

A derivative free projection method for the singularities of vector fields with convex constraints on Hadamard manifolds

ABSTRACT The objective of this paper is to introduce a derivative free projection method designed to find the singularities of pseudomonotone vector fields with convex constraints on Hadamard manifolds. This innovative approach combines the hyperplane projection method with a novel search direction. The global convergence of the proposed method is established under certain conditions. Our method improves some existing results in the literature on Hadamard manifolds. Additionally, illustrative numerical examples are provided to demonstrate the practical efficacy of our method.

A volume‐of‐solid implicit volume penalty method for moving‐body flows

AbstractAn original Immersed Boundary Method for solving moving body flows is proposed. This method couples (i) a Lagrangian Volume‐of‐Solid description of the solid object avoiding conservation issues and (ii) a robust implicit volume penalty forcing embedded in a low‐Mach number projection method to account for the solid's impact on the fluid dynamics. A new composite velocity field is introduced to describe both solid and fluid domains in a single set of governing equations. The accuracy of the method has been assessed on several academic cases, involving stationary or moving bodies and with different mesh resolutions. The predicted forces on the solid are in excellent agreement with body‐fitted reference cases. The system of equations is also proven to be fully mass conservative. Application of the method on a two‐dimensional vertical axis turbine case shows a reduction in computational cost compared to a body‐fitted method.

A novel sensitivity analysis method for multi-input-multi-output structures considering non-probabilistic correlations

In practical engineering, a multi-input-multi-output (MIMO) structure generally features a significant number of correlated input parameters and output responses. Sensitivity analysis is usually adopted to select key parameters for improving the computational efficiency of structural analysis and design processes. Traditional sensitivity analysis methods based on probabilistic models for MIMO structures may not reliably and efficiently derive the sensitivity indexes of correlated input parameters with limited samples. To solve the above problems, a novel sensitivity analysis method for MIMO structures considering non-probabilistic correlations is proposed to estimate the influence of uncertainties and correlations among the parameters on the responses in a unified framework. Firstly, a multidimensional parallelepiped (MP) model is employed to quantify the uncertainties and non-probabilistic correlations among the parameters. A new non-probabilistic variance propagation equation based on the MP model is then proposed to derive the non-probabilistic variances of output responses. The non-probabilistic independent, correlated, and total sensitivity indexes of each parameter for multi-input-single-output (MISO) structures are defined according to the non-probabilistic variance contribution rates. A dimensional normalization method and a vector projection method are then adopted to extend the non-probabilistic sensitivity indexes of each parameter for MIMO structures with correlations. Two numerical examples and an experimental example are exemplified to verify the proficiency and efficiency of the currently proposed method.

Exploring Chinese enterprise innovation ecosystem health: a dynamic evaluation method

PurposeThis study identifies a methodology to explore the issues of enterprise innovation ecosystem health (EIEH).Design/methodology/approachFirst, this study constructs the indicator system of EIEH based on the research objective; second, the dynamic vertical projection method (DVPM) and entropy weight method are proposed to analyze the status and influencing factors of EIEH; finally, the future development of EIEH is analyzed using GM (1,1).FindingsIn terms of methodology, the DVPM can effectively analyze EIEH, which can not only analyze the development status and potential of EIEH every year but also analyze the comprehensive state of EIEH for many years. In terms of practice, the value and grade of EIEH in China have been gradually increasing from 2016 to 2020, but the overall development is unbalanced, and five key factors affecting EIEH have been identified. The EIEH in China is predicted to steadily grow from 2021 to 2025.Originality/valueThe analytical method employed in this study can effectively analyze EIEH, which provides a new analytical perspective for the evaluation of EIEH and enriches the research content of the enterprise innovation ecosystem (EIE). By analyzing the results, we can gain a comprehensive understanding of the state of different EIEs, enabling each EIE to design tailored remedial measures to enhance EIEH and achieve sustainable development.

Potential negative impacts of climate change outweigh opportunities for the Colombian Pacific Ocean Shrimp Fishery

Climate change brings a range of challenges and opportunities to shrimp fisheries globally. The case of the Colombian Pacific Ocean (CPO) is notable due the crucial role of shrimps in the economy, supporting livelihoods for numerous families. However, the potential impacts of climate change on the distribution of shrimps loom large, making it urgent to scrutinize the prospective alterations that might unfurl across the CPO. Employing the Species Distribution Modeling approach under Global Circulation Model scenarios, we predicted the current and future potential distributions of five commercially important shrimps (Litopenaeus occidentalis, Xiphopenaeus riveti, Solenocera agassizii, Penaeus brevirostris, and Penaeus californiensis) based on an annual cycle, and considering the decades 2030 and 2050 under the Shared Socioeconomic Pathways SSP 2.6, SSP 4.5, SSP 7.0, and SSP 8.5. The Bathymetric Projection Method was utilized to obtain spatiotemporal ocean bottom predictors, giving the models more realism for reliable habitat predictions. Six spatiotemporal attributes were computed to gauge the changes in these distributions: area, depth range, spatial aggregation, percentage suitability change, gain or loss of areas, and seasonality. L. occidentalis and X. riveti exhibited favorable shifts during the initial semester for both decades and all scenarios, but unfavorable changes during the latter half of the year, primarily influenced by projected modifications in bottom salinity and bottom temperature. Conversely, for S. agassizii, P. brevirostris, and P. californiensis, predominantly negative changes surfaced across all months, decades, and scenarios, primarily driven by precipitation. These changes pose both threats and opportunities to shrimp fisheries in the CPO. However, their effects are not uniform across space and time. Instead, they form a mosaic of complex interactions that merit careful consideration when seeking practical solutions. These findings hold potential utility for informed decision-making, climate change mitigation, and adaptive strategies within the context of shrimp fisheries management in the CPO.

An inertia projection method for nonlinear pseudo-monotone equations with convex constraints

An inertia projection method for nonlinear pseudo-monotone equations with convex constraints

A finite volume approximations for one nonlinear and nonlocal integrodifferential equations

In this paper, the error analysis of the Petrov–Galerkin finite volume element method (FVEM) is investigated for a nonlinear parabolic integro-differential equation that arises in the mathematical modeling of the penetration of a magnetic field into a substance, accounting for temperature-dependent changes in electrical conductivity. Starting from Maxwell’s equations, we derive a one-dimensional model problem, which forms the basis of our analysis. Our main goal is to develop a general framework for obtaining finite volume element approximations and to study the error analysis. For simplicity, we consider only the lowest-order (linear and L-splines) finite volume elements. The novel contribution lies in the application of FVEM to this problem, leading to the establishment of an unconditionally stable numerical scheme and the derivation of optimal error estimates in the L∞(L2(Ω)) and L2(H01(Ω)) norms for both semi-discrete and linearized backward Euler fully-discrete schemes, using a generalized projection method that carefully manages the nonlinear terms. Lastly, numerical experiments are provided to support the theoretical conclusions.

Risk-return analysis of clean energy grid project investment based on integrated ISM and Monte Carlo model

To solve the problem of complex and difficult to quantify factors affecting investment returns and risks in clean energy power grids, this study comprehensively applies the interpretive structural model and Monte Carlo model to the analysis of investment risk-returns in clean energy power grid projects. The interpretive structural model is utilized to analyze project investment returns, while the Monte Carlo model is used to analyze project investment risks. The project investment risk is based on the factor analysis of project investment returns, and key risk factors are identified through 1000 simulations, and the impact of these risks on project returns is quantified. By combining the two, the investability of the project is analyzed. The results showed that grid electricity prices, kilowatt hour subsidies, technology learning rates, total annual sunshine hours, and system power generation efficiency were key factors driving investment returns. The average expected value of investment return was about 20%, and the probability of investment return below 6% was close to 0. The overall project is worth investing in. From this, it can be seen that the research designed investment risk-return analysis methods for clean energy grid projects can effectively distinguish the main factors affecting investment returns and risks, and pre simulate the risk situation of returns. This study can provide reference for investor decision-making.

Мой идеальный университет: физические и нефизические категории среды в представлениях студентов

<p>The article addresses the issue of identifying the needs of modern students in relation to the university educational environment. The study involved 48 architecture students aged 18 to 27 years (M=19.81; Mo=19; SD=1.82), including 83.33% girls (n=40) and 16.67% boys (n=8). The aim was to identify the most significant categories of the university educational environment. The research, which utilized a projective method – an essay titled "My Ideal University" – and content analysis of the responses, revealed that students consider non-physical categories to be the most important for effective and comfortable study. These categories include the organization of the educational process, the quality of the teaching staff, the curriculum, and opportunities for personal development. To confirm these results, a chi-square test was conducted, showing that non-physical categories of the educational environment were significantly more important than physical ones (χ2=14.812, df=1, p=0.001). The most prominent physical environment categories mentioned by students included the equipment of offices and classrooms, the aesthetic qualities of the space, well-organized university grounds, coworking spaces, and rest areas in the interior. The data obtained can provide practical recommendations for designing new campuses or renovating and reconstructing existing universities. Precisely determining the optimal conditions for an effective and comfortable educational process will help avoid excessive financial investments in improving the physical environment.</p>

Koopman–Hill stability computation of periodic orbits in polynomial dynamical systems using a real-valued quadratic harmonic balance formulation

In this paper, we generalize the Koopman–Hill projection method, which was recently introduced for the numerical stability analysis of periodic solutions, to be included immediately in classical real-valued harmonic balance (HBM) formulations. We incorporate it into the Asymptotic Numerical Method (ANM) continuation framework, providing a numerically efficient stability analysis tool for frequency response curves obtained through HBM. The Hill matrix, which carries stability information and follows as a by-product of the HBM solution procedure, is often computationally challenging to analyze with traditional methods. To address this issue, we generalize the Koopman–Hill projection stability method, which extracts the monodromy matrix from the Hill matrix using a matrix exponential, from complex-valued to real-valued formulations. In addition, we propose a differential recast procedure, which makes this real-valued Hill matrix immediately available within the ANM continuation framework. Using as an example a nonlinear von Kármán beam, we demonstrate that these modifications improve computational efficiency in the stability analysis of frequency response curves.

Pyrolysis front detection in carbon phenolic composites using x-ray computed tomography

Carbon phenolic composites are used as thermal protection systems (TPS) materials on space capsules to protect them from the hot aerothermal environment. The phenolic resin in the composite material decomposes (pyrolyzes) at low temperatures resulting in a pyrolysis front within the material. The detection of the pyrolysis front after exposure to heat has historically been achieved by physically sectioning cross-sections of the material. We combine the phase contrast retrieval method to reconstruct x-ray computed tomography scans along with image convolution to identify the pyrolysis front in carbon phenolic composites. Unlike the standard filtered back projection method that captures only the carbon phase, the phase contrast retrieval method uses both the attenuation coefficients and refractive indices to illuminate all three phases (carbon, resin, and voids) of carbon phenolic composites. Image convolution is applied on scans reconstructed using the phase contrast retrieval method to develop a density map of the composite to locate the pyrolysis front. The analysis is performed on a sample of phenolic impregnated carbon ablator that was tested in an arc-jet facility. For the sample analyzed, the depth of the pyrolysis front from the surface of the sample is calculated to be 2.150 ± 0.148 mm. Although the proposed approach is applied to detect the pyrolysis front, the tools can be used to illuminate the structure of any carbon phenolic composite, and we propose the use of the phase contrast retrieval method as a methodological standard to analyze carbon phenolic composites used on space capsules.

Determination of equivalent crack length for voids in metallic alloys based on continuum damage mechanics modeling

Metals contain different kinds of spatial defects significantly reducing the fatigue performance. Accurate defect-based life prediction methods are required to improve structural integrity analysis and life design reliability. The present work developed a method to determine the equivalent crack length for defects based on continuum damage mechanics. The spatial effects of defects in the calculation of the equivalent crack were quantified and verified by fatigue tests. It is confirmed that the equivalent crack length of both slit and elliptic defects is affected not only by the defect geometry but also by the applied load. Based on the equivalent crack and combined with Paris’ law, the predicted fatigue lives of various slit holes under different loading orientations are within the double scatter band and are much more accurate than the conventional projection method.

A concept for non-uniform thermal irradiation emulation in an immersive virtual environment

This study addresses the challenge of emulating human thermal environments without the need to build physical mock-ups. The aim is to complement the established technology of emulating visual environments with head-mounted displays. For the user, the virtual environment (VE) emulates an arbitrary indoor environment including visual and thermal aspects. In contrast to conventional climate chambers, we describe a concept to emulate arbitrary non-uniform environments and room geometries without the need to construct or modify separate physical mock-ups for each scenario being tested. By fully emulating air temperatures as well as the thermal irradiation, a user can experience the same thermal sensation as in the actual environment. An air conditioning system and nine supply air diffusers are used for the air temperature and humidity control. For thermal radiation, 45 temperature-controlled surfaces are arranged in a hemicube around the user. An arbitrary environment’s thermal irradiation is emulated by a projection of temperatures on the hemicube surface elements. This study compares two methods for setting the surface temperatures in the VE to emulate thermal irradiation. Finally, it presents the results of computational fluid dynamic simulations that benchmark the capability of the VE to emulate a non-uniform indoor thermal environment. For the non-uniform thermal environment benchmark scenario, the assumption of a uniform enclosure (using the surface average radiant temperature) resulted in a surface root mean square error of 2.2 K (local deviation of up to 4.6 K) of radiant temperature on the person dummy surface. The projection method was implemented for the VE, utilising temperature-controlled surfaces. Depending on the projection method used to determine the surface temperatures, it was possible to decrease the root mean square error of the radiant temperature in the emulated environment to a range of 0.4 K to 0.7 K.

Limit Cycles of the Three-dimensional Quadratic Differential System via Hopf Bifurcation

تم في هذه الدراسة النظر في النظام التفاضلي التربيعي ثلاثي الأبعاد، حيث يصبح نقطة الأصل الإحداثيات نقطة توازن هوبف. تم دراسة وجود واستقرار الدورات النهائية التي تنبثق من نقطة هوبف. يتم حساب معاملات ليبانوف المرتبطة بنقطة هوبف باستخدام طريقة الإسقاط. أولاً، تم تحديد أربع عائلات من شروط المعلمات التي من خلالها يمكن للنظام التفاضلي التربيعي ثلاثي الأبعاد أن يظهر البعد الثالث لتشعب هوبف. تم إعطاء الدليل التحليلي لكل مجموعة من الحالات المعلمية عن طريق حساب معاملات ليبانوف، تصفير لقيمة معاملات ليبانوف الأولى و الثاني و غيرالصفري لمعاملات ليبانوف الثالثة. تم تقديم الشروط الواضحة لوجودية واستقرارية ثلاث دورات النهائية ناشئة عن كل عائلة من تشعبات هوبف. يُظهر ناتج الوجود نقطة هوبف مستقرة (غير مستقرة)، مصحوبة بظهور دورتين حديتين مستقرتين (غير مستقرة) جنبًا إلى جنب مع دورة حدية واحدة غير مستقرة (مستقرة) في جوار النقطة الأصل غير المستقر (المستقر) لنظام المعادلة التربيعية ثلاثية الأبعاد. بالإضافة إلى ذلك، يتم استخدام النتيجة لاستكشاف الدورات النهائية لنظام الجذب الفوضوي n-scroll، والذي له العديد من الاستخدامات العملية، بما في ذلك الاتصال الآمن، والتشفير، وتوليد الأرقام العشوائية، والروبوتات المتنقلة المستقلة. تم اشتقاق الشروط التي بموجبها تصبح نقطة الأصل لهذا النظام هي نقطة هوبف، ويمكن أن توجد ثلاث دورات نهائية حول نقطة هوبف. وأخيرًا، توضح العروض العددية أن النظام يخضع لتشعب هوبف فوق الحرج، مما يؤدي إلى دورتين حديتين مستقرتين وواحدة غير مستقرة. وعلاوة على ذلك، تم التحقق من كافة النتائج.

Enhancing coral restoration practices in Seychelles: benefits and limitations of fishing lines and rope as coral stocking methods

Coral restoration plays a pivotal role in mitigating the decline of coral reefs, increasing the need for implementing effective techniques and methodologies. This study investigates the efficacy of stocking Acropora muricata and Pocillopora grandis using fishing line versus rope in mid‐water floating nurseries, offering valuable insights for coral restoration practitioners. Over 1 year, survival, tissue cover, growth, cleaning time, cost, preparation, and stocking timing for both methods were evaluated. Fishing line reduced contact with fouling organisms, contributing to enhanced coral tissue cover and growth rates for P. grandis compared to rope, but no significant effect was detected for A. muricata. Survival differed among species, with higher rates for P. grandis compared to A. muricata, indicating no impact due to stocking methods but species‐specific differences. Challenges like nursery collapses and amphipod outbreaks may have impacted survival, emphasizing the importance of consistent maintenance and accessibility of project sites. Furthermore, the fishing line method reduced cleaning effort. However, cost considerations and preparation complexities for fishing line warrant careful evaluation, particularly with regards to project budgets. The study underscores the necessity for further research, incorporating diverse genotypes, species, and initial fragment sizes to refine restoration strategies. In summary, this study provides important guidance for coral restoration practitioners, aiding informed decisions on stocking methods for different projects and species while considering the balance between coral health benefits and operational feasibility.

A Risk Management Application by Failure Mode and Effect Analysis (FMEA) Method in A Road Drainage Channel Construction Project at H.M Ardan Street of South Sangatta District East Kutai, Indonesia

A construction project of road drainage channel in H.M Ardan Street, South Sangatta District (Multy Years) is included into type of construction project with high level of risk and work accidents since it has large number of workers, the use of sophisticated work tools and machines that require special methods and skills also strong supervision in its usage. These matters could bring undesirable impact potentiality in particular for the occupational safety and health aspect. A negligence of OSH implementation in the construction project can lead to work accident risk within the project. A work safety management is a part of management aspect with function to prevent any work accidents. Its prevention can be done by controlling the occurrence of high-potential work accidents whether in terms of consequences, occurrence probability, also simplicity in its detection. Many safety management methods have been introduced as method that able to be used for potential work accident identification, or measure the level of work accident’s risk, also for evaluating the work accidents; which leads to the Failure Mode and Effect Analysis (FMEA) method as the most appropriate method to achieve the objectives as described above. The selected method for this research was Failure Mode and Effect Analysis (FMEA) method, whereas the data source of this research were primary data obtained from interviews and questionnaires, and secondary data obtained from site plan drawings and identification data of the construction of drainage channels on H.M Ardan Street of South Sanggata District (Multi Years). According to FMEA analysis, there were 15 dominant risks with RPN values above the average value with 4 risks having a value of 48 as the highest RPN value found in this study. Type of risks with the highest RPN value were (a) stricken by heavy equipment and materials during loading and unloading construction materials; (b) fatigue due to an overly busy mobilization schedule; (c) workers fall while installing the formwork; (d) workers’ hand was pierced by nail or getting hit by hammer or wood. Furthermore, by the domino analysis conducted for this research, it produced several precautions and prevention recommendations that grouped into three main stages: Lack of Control, Basic Causes, and Immediate Causes.

Reynolds and Mach Number Effects on Propulsive Performance for a Pitching Airfoil

In this work, numerical simulations are conducted to investigate the effects of Reynolds (Re) and Mach (Ma) numbers on thrust characteristics for a pitching airfoil. The results show that as Re increases, the thrust performance is improved. The inverse square root of Reynolds number is demonstrated to be a universal scaling law for both thrust coefficients and drag-to-thrust crossovers across Re=1×103∼1×106 and Ma=0∼0.3. In contrast, as Ma increases above 0.1, the thrust performance is significantly reduced, especially when Ma approaches 0.3. The thrust coefficients follow the square law of the Mach number, which also exhibits universality. Furthermore, the incompressible vortex projection method and the compressible vortex projection method are employed for thrust decomposition. Before this, the full expression of the compressible vortex projection method is derived. It is revealed that as Re increases, the improvement of thrust performance is primarily attributed to the reduced flow viscous effect and, meanwhile, benefits from the formation of more intense boundary layers and vortex structures in near wake. As Ma increases, the enhancement of local flow compressibility ultimately leads to the divergence of added mass drag and thereby reduces the thrust performance.