Scale Cloud Research Articles

The Cold Interstellar Medium of Galaxies in the Local Universe

The cold interstellar medium (ISM) plays a central role in the galaxy evolution process. It is the reservoir that fuels galaxy growth via star formation, the repository of material formed by these stars, and a sensitive tracer of internal and external processes that affect entire galaxies. Consequently, significant efforts have gone into systematic surveys of the cold ISM of the galaxies in the local Universe. This review discusses the resulting network of scaling relations connecting the atomic and molecular gas masses of galaxies with their other global properties (stellar masses, morphologies, metallicities, star-formation activity…) and their implications for our understanding of galaxy evolution. Key take-home messages are as follows: ▪ From a gas perspective, there are three main factors that determine the star-formation rate of a galaxy: the total mass of its cold ISM, how much of that gas is molecular, and the rate at which any molecular gas is converted into stars. All three of these factors vary systematically across the local galaxy population. ▪ The shape and scatter of both the star-formation main sequence and the mass–metallicity relation are deeply linked to the availability of atomic and molecular gas. ▪ Future progress will come from expanding our exploration of scaling relations into new parameter space (in particular, the regime of dwarf galaxies), better connecting the cold ISM of large samples of galaxies with the environment that feeds them (the circumgalactic medium, in particular), and understanding the impact of these large scales on the efficiency of the star-formation process on molecular cloud scales.

Systematic Investigation of Dust and Gaseous CO in 12 Nearby Molecular Clouds

We report on the first uniform and systematic study of dust and molecular gas in nearby molecular clouds. We use surveys of dust extinction and emission to determine the opacity and map the distribution of the dust within a dozen local clouds in order to derive a uniform set of basic cloud properties. We find (1) the average dust opacity 〈κ d,353〉 = 0.8 cm2 g−1 with variations of a factor of ∼2 between clouds, (2) cloud probability density functions are exquisitely described by steeply falling power laws with a narrow range of slope, and (3) a tight scaling relation for the cloud sample, indicative of a cloud population with an exactingly constant average surface density above a common fixed boundary. We compare these results to uniformly analyzed CO surveys. We measure the CO mass conversion factors and assess the efficacy of CO for tracing the physical properties of molecular clouds. We find 〈α CO〉 = 4.31 ± 0.67 M ⊙ (K km s−1 pc2)−1 (corresponding to X CO = 1.97 ×1020 cm−2(K km s−1)−1). We demonstrate that CO observations are a poor tracer of column density and structure on sub-cloud spatial scales. On cloud scales, CO observations can provide measurements consistent with those of the dust, provided data are analyzed in a similar, self-consistent fashion. Measurements of average giant molecular cloud surface density are sensitive to choice of cloud boundary. Care must be exercised to adopt common fixed boundaries when comparing surface densities for cloud populations within and between galaxies.

Effects of cloud size and built-in obstacles on hydrogen cloud explosion using large eddy simulation

The purpose of this work is to evaluate hydrogen cloud explosion using large eddy simulation. The LES model combined with acoustical theory is firstly established and validated. Then the effects of cloud scale on flame dynamics and explosion pressure are explored. Finally, the effects of obstacle-induced turbulence on hydrogen cloud explosion are analyzed. The research works indicated that the LES model combined with acoustical theory could be able to reproduce flame acceleration and explosion pressure evolution. Maximum explosion pressure and maximum flame front velocity continue to increase with increasing cloud scale. The deviation values of flame radius of four cloud scales are 0.25 m, 0.5 m and 0.75 m, once beyond the critical value, the flame front velocity of larger cloud scale is lower than that of smaller cloud scale. The increase rate of flame front velocity and explosion pressure, not their peak value, will be certainly increased by built-in obstacles, which could be attributed to the couplings of turbulent vortex and moving flame.

Spatially resolved star-formation relations of dense molecular gas in NGC 1068

Context. According to the current understanding of star formation (SF), the regulation of this phenomenon in galaxy disks reflects a complex balance between processes that operate in molecular gas on local cloud scales as well as on global disk scales. Aims. We analyse the influence of the dynamical environment on the SF relations of the dense molecular gas in the starburst (SB) ring of the Seyfert 2 galaxy NGC 1068. Methods. We used ALMA to image the emission of the 1–0 transitions of HCN and HCO+, which trace dense molecular gas in the r ∼ 1.3 kpc SB ring of NGC 1068, with a resolution of 56 pc. We also used ancillary data of CO(1–0) as well as CO(3–2) and its underlying continuum emission at the resolutions of ∼100 pc and ∼40 pc, respectively. These observations allow us to probe a wide range of molecular gas densities (nH2 ∼ 103 − 5 cm−3). The star-formation rate (SFR) in the SB ring of NGC 1068 is derived from Paα line emission imaged by HST/NICMOS. We analyse how different formulations of SF relations change depending on the adopted aperture sizes and on the choice of molecular gas tracer. Results. The scatter in the Kennicutt–Schmidt relation, linking the SFR density (ΣSFR) with the (dense) molecular gas surface density (Σdense), is about a factor of two to three lower for the HCN and HCO+ lines compared to that derived from CO(1–0) for a common aperture. Correlations lose statistical significance below a critical spatial scale of ≈300−400 pc for all gas tracers. The SF efficiency of the dense molecular gas, defined as SFEdense ≡ ΣSFR/Σdense, shows a scattered distribution as a function of the HCN luminosity (L′(HCN)) around a mean value of ≃0.01 Myr−1. An alternative prescription for SF relations, which includes the dependence of SFEdense on the combination of Σdense and the velocity dispersion (σ), resolves the degeneracy associated with the SFEdense − L′(HCN) plot. The SFEdense values show a positive trend with the boundedness of the gas, measured by the parameter b ≡ Σdense/σ2. We identify two branches in the SFEdense − b plot that correspond to two dynamical environments within the SB ring; they are defined by their proximity to the region where the spiral structure is connected to the stellar bar. This region corresponds to the crossing of two overlapping density wave resonances, where an increased rate of cloud-cloud collisions would favour an enhanced compression of molecular gas. Conclusions. These results suggest that galactic dynamics plays a major role in the efficiency of the conversion of gas into stars. Our work adds supporting evidence that density-threshold SF models, which argue that the SFEdense should be roughly constant, fail to account for spatially resolved SF relations of dense gas in the SB ring of NGC 1068.

WISDOM Project – X. The morphology of the molecular ISM in galaxy centres and its dependence on galaxy structure

ABSTRACT We use high-resolution maps of the molecular interstellar medium (ISM) in the centres of 86 nearby galaxies from the millimetre-Wave Interferometric Survey of Dark Object Masses (WISDOM) and Physics at High Angular Resolution in Nearby GalaxieS (PHANGS) surveys to investigate the physical mechanisms setting the morphology of the ISM at molecular cloud scales. We show that early-type galaxies tend to have smooth, regular molecular gas morphologies, while the ISM in spiral galaxy bulges is much more asymmetric and clumpy when observed at the same spatial scales. We quantify these differences using non-parametric morphology measures (Asymmetry, Smoothness, and Gini), and compare these measurements with those extracted from idealized galaxy simulations. We show that the morphology of the molecular ISM changes systematically as a function of various large-scale galaxy parameters, including galaxy morphological type, stellar mass, stellar velocity dispersion, effective stellar mass surface density, molecular gas surface density, star formation efficiency, and the presence of a bar. We perform a statistical analysis to determine which of these correlated parameters best predicts the morphology of the ISM. We find the effective stellar mass surface (or volume) density to be the strongest predictor of the morphology of the molecular gas, while star formation and bars maybe be important secondary drivers. We find that gas self-gravity is not the dominant process shaping the morphology of the molecular gas in galaxy centres. Instead effects caused by the depth of the potential well, such as shear, suppression of stellar spiral density waves, and/or inflow, affect the ability of the gas to fragment.

Achieving least privilege at cloud scale with cloud infrastructure entitlements management

Managing identities and permissions for enterprises at cloud scale is a major problem today. Cloud infrastructure entitlement management (CIEM) focuses on cloud access risk by providing enterprises with a robust platform for governance and entitlement controls and managing risk. Scaling out an enterprise’s infrastructure using public cloud comes with its own set of risks, including knowing all the identities that have access to your infrastructure and the permissions that they have once access is permitted. Ignoring the proliferation of identities and their associated permissions increases the potential attack surface for hackers who get access to cloud infrastructure. Implementing the principle of least privilege with CIEM helps enterprises manage their growing cloud infrastructure while keeping security in mind. This paper provides an overview of the problems that enterprises face with managing identities and permissions and how CIEM solutions can be effective for these issues.

Multi‐scale point cloud registration based on topological structure

AbstractThe establishment of point‐to‐point correspondence between point clouds is called three‐dimensional point matching, which is widely used in computer vision, computer graphics, robotics and other fields. When the scale of source point cloud and target point cloud are different, it brings great difficulties to obtain the satisfactory matching result. Therefore, the article proposes a registration algorithm to solve this problem effectively. First, we construct a multi‐scale space related to Gaussian standard deviation. Second, we use a topological similarity of two directed trees constructed by feature points coming from two point clouds for fuzzy matching. Finally, we use local matching and global matching methods to find the corresponding relationship between patches in multi‐scale space. We find the feature correspondence of different scales in multi‐scale space and get the scale factor. Our method improves the accuracy of matching by eliminating mismatch caused by descriptor matching and local geometry matching. We show great performance of our approach by conducting extensive experiments, which outperforms other state‐of‐the‐art methods, in particular, it provides a valuable tool for point cloud registration.

Numerically simulated influence of positive ions on the propagation of a positive streamer initiated in an argon plasma jet

A plasma jet with inert working gas operates in a streamer discharge mechanism. The propagation behavior of streamers determines the distribution of active species, which play a key role in the applications of plasma jets. To make clear streamer behavior under the influence of residual positive ions, a two-dimensional fluid model based on the continuity, the conservation, and Poisson's equations is employed to numerically investigate the dynamic behavior of a positive streamer when it approaches a cloud of positive ions with different densities and scales. Results indicate that the streamer always propagates along the axis and passes through the cloud of positive ions if the ions are rarefied (1.0 × 1016 m−3 in the core), which behaves like a free streamer. If the ion cloud has a medium density (5.0 × 1016 m−3 in the core), the streamer first deflects upward when it approaches the vicinity of the ion cloud and then deflects downward when it departs from the ion cloud, leaving a detouring track. The detouring track is also left if the ions are fairly dense (1.0 × 1017 m−3 in the core). However, the detouring process is fulfilled by the relay of two streamers, which are initiated at the jet nozzle and inside the ion cloud, respectively. Moreover, the velocity of the streamer is simulated with varying ion densities, voltage amplitudes, and gap widths. In addition, the deflection amplitude of the detouring track is investigated as a function of the voltage amplitude, gap width, ion density, cloud position, and cloud scale.

A Review on AWS - Cloud Computing Technology

Abstract: Cloud computing is something simple we can define as maintaining data centers and data servers and also u can access technology services by computing power, storage, and database using cloud computing technology AWS(Amazon Web Services). It is an emerged model which is already popular among almost all enterprises. It provides us the concept of ondemand services where we are using and scaling cloud resources on demand and as per demand respectively. AWS Cloud computing is a cost-effective model. The major concern in this model is Security and Storage in the cloud. This is one of the major reasons many enterprises of choosing AWS cloud computing. This paper provides a review of security research in the field of cloud security and storage services of the AWS cloud platform. After security and storage, we have presented the working of AWS (Amazon Web Service) cloud computing. AWS is the most trusted provider of cloud computing which not only provides excellent cloud security but also provides excellent cloud storage services. The main aim of this paper is to make cloud computing storage and security a core operation and not an add-on operation. As per the increase in the Service provider and related companies, this AWS Cloud Platform plays a vital role in service industries by giving its best web services, so, therefore, choosing the cloud service providers wisely is the basic need of the industry. Therefore we are going to see how AWS fulfills all these specific needs. Keywords: Trusted Computing, AWS, Information-Centric Security, Cloud Storage, S3, EC2, Cloud Computing

A Multi-criteria Decision Making Approach for Scaling and Placement of Virtual Network Functions

This paper investigates the joint scaling and placement problem of network services made up of virtual network functions (VNFs) that can be provided inside a cluster managing multiple points of presence (PoPs). Aiming at increasing the VNF service satisfaction rates and minimizing the deployment cost, we use both transport and cloud-aware VNF scaling as well as multi-attribute decision making (MADM) algorithms for VNF placement inside the cluster. The original joint scaling and placement problem is known to be NP-hard and hence the problem is solved by separating scaling and placement problems and solving them individually. The experiments are done using a dataset containing the information of a deployed digital-twin network service. These experiments show that considering transport and cloud parameters during scaling and placement algorithms perform more efficiently than the only cloud based or transport based scaling followed by placement algorithms. One of the MADM algorithms, Total Order Preference by Similarity to the Ideal Solution (TOPSIS), has shown to yield the lowest deployment cost and highest VNF request satisfaction rates compared to only transport or cloud scaling and other investigated MADM algorithms. Our simulation results indicate that considering both transport and cloud parameters in various availability scenarios of cloud and transport resources has significant potential to provide increased request satisfaction rates when VNF scaling and placement using the TOPSIS scheme is performed.

Stellar winds and photoionization in a spiral arm

ABSTRACT The role of different stellar feedback mechanisms in giant molecular clouds is not well understood. This is especially true for regions with many interacting clouds as would be found in a galactic spiral arm. In this paper, building on previous work by Bending et al., we extract a $500{\, \mathrm{pc}}\times 500{\, \mathrm{pc}}\times {100}{\, \mathrm{pc}}$ section of a spiral arm from a galaxy simulation. We use smoothed particle hydrodynamics to re-simulate the region at higher resolution (1 M⊙ per particle). We present a method for momentum-driven stellar winds from main-sequence massive stars, and include this with photoionization, self-gravity, a galactic potential, and interstellar medium heating/cooling. We also include cluster-sink particles with accretion radii of 0.78 pc to track star/cluster formation. The feedback methods are as robust as previous models on individual cloud scales (e.g. Dale et al.). We find that photoionization dominates the disruption of the spiral arm section, with stellar winds only producing small cavities (at most ∼30 pc). Stellar winds do not affect the resulting cloud statistics or the integrated star formation rate/efficiency, unlike ionization, which produces more stars, and more clouds of higher density and higher velocity dispersion compared to the control run without feedback. Winds do affect the sink properties, distributing star formation over more low-mass sinks (∼102 M⊙) and producing fewer high-mass sinks (∼103 M⊙). Overall, stellar winds play at best a secondary role compared to photoionization, and on many measures, they have a negligible impact.

Monolithic vs. Microservice Architecture: A Performance and Scalability Evaluation

Context. Since its proclamation in 2012, microservices-based architecture has gained widespread popularity due to its advantages, such as improved availability, fault tolerance, and horizontal scalability, as well as greater software development agility. Motivation. Yet, refactoring a monolith to microservices by smaller businesses and expecting that the migration will bring benefits similar to those reported by top global companies, such as Netflix, Amazon, eBay, and Uber, might be an illusion. Indeed, for systems that do not have thousands of concurrent users and can be scaled vertically, the benefits of such migration have not been sufficiently investigated, while the existing evidence is inconsistent. Objective. The purpose of this paper is to compare the performance and scalability of monolithic and microservice architectures on a reference web application. Method. The application was implemented in four different versions, covering not only two different architectural styles (monolith vs. microservices) but also two different implementation technologies (Java vs. C#.NET). Next, we conducted a series of controlled experiments in three different deployment environments (local, Azure Spring Cloud, and Azure App Service). Findings. The key lessons learned are as follows: (1) on a single machine, a monolith performs better than its microservice-based counterpart; (2) The Java platform makes better use of powerful machines in case of computation-intensive services when compared to.NET; the technology platform effect is reversed when non-computationally intensive services are run on machines with low computational capacity; (3) vertical scaling is more cost-effective than horizontal scaling in the Azure cloud; (4) scaling out beyond a certain number of instances degrades the application performance; (5) implementation technology (either Java or C#.NET) does not have a noticeable impact on the scalability performance.

Effect of clouds on emission spectra for super Venus

We report a model study on the effects of clouds on emission spectra of super-Venus planets. Our goal is to assess possible ways to identify characteristic spectral features due to clouds. We show that it is possible to distinguish an impact of H2SO4 clouds on the CO2 absorption band at 4.8 μm for temperature profiles with and without a thermal inversion. The thermal inversion can help to distinguish the signal from high altitude clouds (85 km, ∼1 mbar). Featureless emission spectra are found for high altitude clouds (85 km, ∼1 mbar) with temperature profile without thermal inversion. More spectral features appear in the emission spectra with decreasing cloud top altitudes. The compactness of clouds has an inverse effect on emission spectra than cloud top altitudes. Small cloud scale heights reduce the signal and the CO2 absorption bands become flat.

THE TASKS OF SCALING CLOUD APPLICATIONS FOR THE EDUCATIONAL ENVIRONMENT OF UNIVERSITIES

It is shown that modern cloud technologies in education provide resources to students and teachers as online services. When using a cloud environment, the information will be stored in the cloud. In addition, you do not need to specifically install additional software on your personal computer. In this case, cloud technologies act as a highly effective tool that improves the quality of education and promotes greater mobility of students. It is proved that, speaking about the technical aspects and prospects for the development of cloud applications in the educational process of universities, it is necessary to pay attention to the critical characteristics of cloud solutions in terms of speed and security of information exchange. An algorithm for scaling cloud applications for the digital educational environment of the university, as well as for determining the execution time of a network request, is described. Based on information about the state of the digital educational environment, sets of rules for reactive scaling and evaluating the effectiveness of the university's digital educational environment are formed.

A new model for including galactic winds in simulations of galaxy formation II: Implementation of PhEW in cosmological simulations

ABSTRACT Although galactic winds play a critical role in regulating galaxy formation, hydrodynamic cosmological simulations do not resolve the scales that govern the interaction between winds and the ambient circumgalactic medium (CGM). We implement the Physically Evolved Wind (PhEW) model of Huang et al. in the gizmo hydrodynamics code and perform test cosmological simulations with different choices of model parameters and numerical resolution. PhEW adopts an explicit subgrid model that treats each wind particle as a collection of clouds that exchange mass and metals with their surroundings and evaporate by conduction and hydrodynamic instabilities as calibrated on much higher resolution cloud scale simulations. In contrast to a conventional wind algorithm, we find that PhEW results are robust to numerical resolution and implementation details because the small scale interactions are defined by the model itself. Compared to our previous wind simulations with the same resolution, our PhEW simulations are in better agreement with low-redshift galactic stellar mass functions at M* < 1011M⊙ because PhEW particles shed mass to the CGM before escaping low mass haloes. PhEW radically alters the CGM metal distribution because PhEW particles disperse metals to the ambient medium as their clouds dissipate, producing a CGM metallicity distribution that is skewed but unimodal and is similar between cold and hot gas. While the temperature distributions and radial profiles of gaseous haloes are similar in simulations with PhEW and conventional winds, these changes in metal distribution will affect their predicted UV/X-ray properties in absorption and emission.

Enhancing the Security and Performance of Cloud for E-Governance Infrastructure

E-Governance is getting momentous in India. Over the years, e-Governance has played a major part in every sphere of the economy. In this paper, we have proposed E-MODI (E-governance model for open distributed infrastructure) a centralized e-Governance system for government of India, the implementation of this system is technically based on open distributed infrastructure which comprises of various government bodies in one single centralized unit. Our proposed model identifies three different patterns of cloud computing which are DGC, SGC and CGC. In addition, readiness assessment of the services needs to migrate into cloud. In this paper, we propose energy efficient VM allocation algorithm to achieve higher energy efficiency in large scale cloud data centers when system on optimum mode. Our objectives have been explained in details and experiments were designed to demonstrate the robustness of the multi-layered security which is an integration of High secure lightweight block cipher CSL along with Ultra powerful BLAKE3 hashing function in order to maintain information security triad.

A Novel Blockchain and Bi-Linear Polynomial-Based QCP-ABE Framework for Privacy and Security over the Complex Cloud Data.

As a result of the limited resources available in IoT local devices, the large scale cloud consumer’s data that are produced by IoT related machines are contracted out to the cloud. Cloud computing is unreliable, using it can compromise user privacy, and data may be leaked. Because cloud-data and grid infrastructure are both growing exponentially, there is an urgent need to explore computational sources and cloud large-data protection. Numerous cloud service categories are assimilated into numerous fields, such as defense systems and pharmaceutical databases, to compute information space and allocation of resources. Attribute Based Encryption (ABE) is a sophisticated approach which can permit employees to specify a higher level of security for data stored in cloud storage facilities. Numerous obsolete ABE techniques are practical when applied to small data sets to generate cryptograms with restricted computational properties; their properties are used to generate the key, encrypt it, and decrypt it. To address the current concerns, a dynamic non-linear polynomial chaotic quantum hash technique on top of secure block chain model can be used for enhancing cloud data security while maintaining user privacy. In the proposed method, customer attributes are guaranteed by using a dynamic non- polynomial chaotic map function for the key initialization, encryption, and decryption. In the proposed model, both organized and unorganized massive clinical data are considered to be inputs for reliable corroboration and encoding. Compared to existing models, the real-time simulation results demonstrate that the stated standard is more precise than 90% in terms of bit change and more precise than 95% in terms of dynamic key generation, encipherment, and decipherment time.

Impact of relativistic jets on the star formation rate: a turbulence-regulated framework

ABSTRACT We apply a turbulence-regulated model of star formation to calculate the star formation rate (SFR) of dense star-forming clouds in simulations of jet–interstellar medium (ISM) interactions. The method isolates individual clumps and accounts for the impact of virial parameter and Mach number of the clumps on the star formation activity. This improves upon other estimates of the SFR in simulations of jet–ISM interactions, which are often solely based on local gas density, neglecting the impact of turbulence. We apply this framework to the results of a suite of jet–ISM interaction simulations to study how the jet regulates the SFR both globally and on the scale of individual star-forming clouds. We find that the jet strongly affects the multiphase ISM in the galaxy, inducing turbulence and increasing the velocity dispersion within the clouds. This causes a global reduction in the SFR compared to a simulation without a jet. The shocks driven into clouds by the jet also compress the gas to higher densities, resulting in local enhancements of the SFR. However, the velocity dispersion in such clouds is also comparably high, which results in a lower SFR than would be observed in galaxies with similar gas mass surface densities and without powerful radio jets. We thus show that both local negative and positive jet feedback can occur in a single system during a single jet event, and that the SFR in the ISM varies in a complicated manner that depends on the strength of the jet–ISM coupling and the jet break-out time-scale.

Investigation of the hazardous area in a liquid hydrogen release with or without fence

Constructing a fence for potential liquid hydrogen leakage is a common protective measure to prevent the unrestricted spread, and critically evaluating the effects of a fence is essential for the safe use of hydrogen energy. Based on NASA's large-scale experiment of liquid hydrogen release, a 3D numerical model considering the existence of fence is proposed to study the dynamic spread behaviors of hydrogen flammable cloud and liquid hydrogen pool. The results show that the liquid hydrogen pool keeps a downwind radius of about 1.75 m most of the time during the release, and the hydrogen flammable cloud has a limit spread distance. Three cases are set to comparatively evaluate the effect of the fence, which are full fence, downwind half fence and no fence. Under the three cases, liquid hydrogen pools all evaporate completely within 5 s. Full fence scenario has the modest spread scale of hydrogen flammable cloud in the atmosphere but the longest duration for 86 s, and the upwind fence causes an easily overlooked hazardous region due to the vortex here, thus constructing a full fence is not an ideal strategy when the spread direction is constant. Just constructing a downwind half fence leads to the greatest spread distance of the flammable hydrogen cloud, which are 33.6 m and 68 m in vertical and downwind directions. No fence case corresponds to the smallest diffusion scale of flammable hydrogen cloud in atmosphere but the longest near-ground spread distance for 43.35 m. Four stages can be divided to summarize the entire life period of the flammable cloud for the cases with and without a fence, while three stages for the case with a downwind half fence.

Reliability concept drift online measurement for composite cloud systems

Benefiting from the pay-as-you-go business paradigm, the scale of the global cloud computing industry grows rapidly. It has become a possible way to dynamically integrate and cooperate RESTful and SOAP-based component cloud services to develop large-scale complex software systems based on service composition techniques. The constructed composite cloud systems run under dynamic and uncertain operating environments. The issue of how to deal with the concept drift of the reliability data streams to guarantee a stable execution of composite cloud systems has become a grand challenge. To provide some early guidance and act as a trigger mechanism for composite cloud systems reliability adaptation during the system operation and maintenance, we propose a reliability concept drift measurement approach via Sinkhorn distance for composite cloud systems (or RCDMeas) in this paper. This method employs entropy regularization and fixed-point iteration to identify the reliability concept drift between the historical accumulated reliability flow data and the up-to-date reliability flow data. Large-scale data experiments verified the effectiveness of the proposed approach.