Critical Penetration Research Articles

Fluid-induced vibration evolution mechanism of multiphase free sink vortex and the multi-source vibration sensing method

The multiphase free sink vortex (MFSV) has frequently appeared in practical industry processes, including the refinement of steel stream, hydroelectric energy conversion of the tidal power station, and draining state detection of nuclear power equipment. Its internal real-time monitoring is crucial for enhancing product yield, raising energy utilization, and achieving safe and high-effective production. However, harsh industrial conditions, such as high temperature, reactivity disturbance, and high-frequency shock, prevent the direct detection of the MFSV flow field. Given the above issues, this paper proposed a novel fluid–structure coupling modeling and sensing method for the MFSV-induced vibration mechanism. A fluid–structure coupling mechanic model based on the Rankine vortex model and Helmholtz equation is built to determine critical penetration conditions. Then, a Flügge equation-based solving approach is proposed to obtain the vibration evolution mechanism. Forced displacement response and vibration characters are discussed with the multi-source vibration sensing methods (MSVSM). Finally, a wavelet packet (WP) transform-based vibration sensing technique is presented to identify the distortion attribute in the critical transition state. The results show that the proposed modeling and solution method oriented to the MFSV-induced vibration have better revealed the vibration evolution mechanism and its displacement response. Flow flux dominates the critical transition time and vibration intensities of the MFSV flow field; the WP transform-based sensing method can effectively identify transient distortion attributes. The relevant result can offer a helpful reference for fluid-induced vibration detection and provide technical solutions for industrial monitoring systems.

PatrIoT: practical and agile threat research for IoT

The Internet of things (IoT) products, which have been widely adopted, still pose challenges in the modern cybersecurity landscape. Many IoT devices are resource-constrained and almost constantly online. Furthermore, the security features of these devices are less often of concern, and fewer methods, standards, and guidelines are available for testing them. Although a few approaches are available to assess the security posture of IoT products, the ones in use are mostly based on traditional non-IoT-focused techniques and generally lack the attackers’ perspective. This study provides a four-stage IoT vulnerability research methodology built on top of four key elements: logical attack surface decomposition, compilation of top 100 weaknesses, lightweight risk scoring, and step-by-step penetration testing guidelines. Our proposed methodology is evaluated with multiple IoT products. The results indicate that PatrIoT allows cyber security practitioners without much experience to advance vulnerability research activities quickly and reduces the risk of critical IoT penetration testing steps being overlooked.

Tradition as Body

Abstract Coming from the perspective of embodied or enactive cognition, this article argues for the bodily roots of all tradition. Given that tradition entails a givenness inherited from the past meeting with interpretation/modification/construction in the present, it examines tradition as an aspect of self-organizing cultural, particularly religious, systems, including in situations far from equilibrium. Building upon Michael Polanyi’s idea that what we tacitly rely upon becomes incorporated into our bodies, the article takes a phenomenological approach to argue that traditions function as part of our bodies through which we meaningfully engage the world. As such, tradition sets limits to our critical penetration, as much of our knowledge is unspecifiable. The Enlightenment ideal that all tradition is thoroughly contestable – open to explicitation and needing justification – remains strong in the academy. The article examines both the pitfalls of critical reflection and when critical reflection is appropriate or necessary.

Torpedo pile penetration by combined water jet and mechanical vibrations in cohesive sedimentary beds

The penetration efficiency and safety of piles on the seabed affect the cost of offshore structures and the reliability of relevant equipment, which entails to the success or failure of the development and utilization of ocean resources. However, the traditional methods of pile penetration, including pressing method, impact driving method and vibro-driving method, are difficult to adapt to the complex marine environment. In this study, the torpedo pile penetration in cohesive sedimentary bed was investigated by applying downwardly directed vertical water jet and mechanical vibrations. The experimental work was developed in the laboratory through a series of pile penetration tests in different types of cohesive sediments. During the penetration processes of the torpedo pile, the relevant influencing factors such as water content of cohesive sediment, vibration intensity and water jet velocity were considered. The experimental results show that the penetration depth of the torpedo pile increases with the increase of water jet velocity, vibration intensity and water content of cohesive sediment. Based on the dimensionless analysis and data regression, a formula for the critical penetration depth of the torpedo pile in cohesive sediment is proposed, which is correlated with the water jet velocity and vibration intensity, as well as the torpedo pile and soil properties. In addition, the formula is verified by the experimental data of other study, which presents good consistency.

An approximate contact pressure for normal penetration of rigid ogive projectiles into metal targets

An approximate analytical expression for the contact pressure applied by a metal target to a rigid ogive projectile is determined by generalizing the analytical expressions developed previously for penetration of a rigid ovoid of Rankine into an incompressible elastic-perfectly-plastic target. Two empirical shape factors are introduced and determined which model the geometric dependences of the terms in the contact pressure due to the target’s yield strength and inertia. Analytical expressions are determined for the resistance to penetration which depend on the ogive’s shape and which determine the critical penetration velocity for the onset of separation of the target material from the projectile’s nose. Also, a procedure for determining the effective yield strength of a general target material is presented. Results of numerical simulations for different ogives and different target materials are used to validate the proposed analytical equations. Some results are compared with experimental data.

Foreign object damage and post-impact tensile behavior of plain-woven SiC/SiC composites

Plain-woven SiC/SiC composite plates, fabricated using the chemical vapor infiltration (CVI) technology, were impact-tested at different velocities using 3-mm-diameter steel spheres. The states of the impacted targets were divided into three categories: surface damage, critical penetration, and full penetration. The microstructures of the foreign object damage (FOD) in the targets were carefully observed using microscope and X-ray computerized tomography (CT) scans. Based on the results of the observations, the forms of impact damage of ceramic matrix composites (CMCs), including cone cracking, yarn fracture and bending, and delamination, are revealed and summarized. The mechanisms of the penetration process were further analyzed by combining these damage modes of the CMCs. Subsequently, tensile tests of the impacted specimens were performed to investigate the effect of FOD on the tensile behavior of the CMCs. The digital image correlation (DIC) method was used to obtain the strain distribution of the impacted targets during tension. The tensile curves of the undamaged and impacted specimens were obtained and compared. The evolution of the tensile failure of the damaged beams was then analyzed. Finally, the residual strengths of CMC plates impacted at different velocities were compared.

Failure criterion of double-plate vertically loaded anchor in saturated marine fine sand under monotonic loading

The critical penetration depth and failure displacement of vertically loaded anchor (VLA) have already been investigated. However, only few investigations focused on the double-plate VLA. Therefore, based on the finite element method, the critical penetration depth for the double-plate VLA was obtained, which is approximately 6.0 times the width of the upper fluke of the double-plate VLA. According to the reduced-scale model tests, the failure displacement of the double-plate VLA with different included angles and dimensions of the bottom fluke under shallow-embedded and deep-embedded conditions was obtained. Furthermore, the failure displacement of double-plate VLA with 30° included angle and the dimension of bottom fluke equal to that of upper fluke under shallow-embedded and deep-embedded condition is 0.29 and 0.67 times the width of upper fluke, respectively. Based on the empirical bearing capacity formula for VLA model, an improved bearing capacity formula for double-plate VLA model has been put forward; by means of the improved bearing capacity formula, the coefficient of bearing capacity for double-plate VLA under shallow-embedded and deep-embedded condition is obtained to be 5.013 and 4.106, respectively.

Effect of low-temperature thermal annealing on the vortex dynamics of metastable β-Bi2Pd single crystals

We study the vortex dynamics on β-Bi2Pd single crystals with a superconducting critical temperature of 5.1 K. The upper critical fields and magnetic penetration depth are determined from magnetization measurements. At low temperatures, the self-field critical current density (Jc) is ≈ 20 kA/cm2. The vortex pinning energy, extracted from an Anderson-Kim approximation, is between 340 K and 140 K for fields between 100 G and 600 G. Differential scanning calorimetric measurements show that the crystals start to transform into the alpha-phase at temperatures as low as 60 °C. Short annealing at 100 °C modifies the pinning landscape increasing Jc mainly at temperatures below 3 K. The angular dependence of Jc from electrical transport experiments shows a broad peak when the magnetic field is parallel to the crystallographic c-axis, indicating the presence of correlated disorder.

Role of Y substitution for Ca-site on magneto-resistivity properties of Bi-2212 superconductor rods prepared by LFZ

This comprehensive study delves into the effect of partial Y3+ substitution for Ca2+ in Bi2Sr2CaCu2O8+y superconducting rods prepared by the laser floating zone method (LFZ). The critical transition temperatures (Tconset, Tc, Tcoffset), activation energy (U), irreversibility field (Hirr), upper critical magnetic field (Hc2), coherence length (ξ), and penetration depth (λ) are determined by means of magneto-resistivity measurements performed between 0 and 5 T. According to the resistivity-temperature graph for zero fields, Tcoffset values tend to decrease regularly from 90.8 K to 87.1 K, and the residual resistivity values increase steadily from 0.14 to 9.7 mΩ .cm with the Y-content. The change of these two parameters is a sign that Y-introduction into the Bi-2212 matrix undermines the inter-grain coupling and increases the level of permanent-defects in the crystalline structure. However, the relatively high Tcoffset values and extremely low residual resistivity, especially in the pure and low Y-substituted samples, reflect the success of the LFZ process in growing homogeneous and well-oriented Bi-2212 grains. The resistivity transition broadening is observed when the applied field increases and Tcoffset values decrease dramatically, i.e. from 90.8 K to 72.1 K for the pure sample and from 87.1 K to 48.2 K for the 0.20Y-substituted ones. The calculated U values using the TAFF model decrease with the increase of the Y-content and the magnetic field. In addition, the magnetic field and temperature dependence of U is expressed by using U(H,T) ∼ ΔT H−η equation. Deduced parameters of Hirr and Hc2 from magneto-resistivity curves and theoretical findings of ξ and λ also favor the degradation of U values with the augmentation of Y-content in the Bi-2212 rods.

Selective penetration behavior of microgels in superpermeable channels and reservoir matrices

Gel treatment is an effective way to attack excessive water production in many mature oilfields around the world. Selective penetration is desired for successful gel treatments. That is, gel materials should easily penetrate the target zones (i.e., channeling features such as superpermeable channels) without entering/damaging the nontarget zones (i.e., reservoir matrices or oil zones). This study revealed that presence of threshold penetration pressure (ΔPth) was responsible for selective penetration behavior of tested microgels. The concept of ΔPth was utilized to figure out favorable working conditions for effective gel treatments. Microgel dispersions were injected into superpermeable (super-k) sandpacks (mimicking super-k channels in reservoirs, 60–221 darcies), heterogeneous models with super-k channels (79–230 darcies), and sandstone cores (mimicking reservoir matrices, 50–5000 md). The results demonstrated that a minimum differential driving pressure (i.e., threshold penetration pressure, ΔPth) was required to push microgel particles to penetrate channels or matrices. The critical penetration behavior was closely related to the particle/pore size ratio. Low ΔPth at smaller particle/pore ratios was beneficial to allow easy penetration of gel materials into the channeling zones. On the contrary, high ΔPth at larger particle/pore ratios was desirable to prevent gel materials from massively invading and damaging the matrices. Instead, the gel particles accumulated at the inlet surface, and a gel cake was gradually formed. The cake further prevented the invasion of the gels. The cake could be removed by chemical breakers to resume the injectivity/productivity of the matrices. Correlations were developed to describe the relationship between ΔPth and particle/pore ratio. A distinct transition was identified at the particle/pore ratio of about 3. This work could help identify the favorable conditions to achieve successful gel treatments. In an effective conformance treatment, the particle/pore ratio in the channel should be sufficiently low to allow easy penetration of gel materials into the channel (e.g., particle/pore ratio<2 in this study). Meanwhile, the particle/pore ratio in the matrix should be large enough to support a high ΔPth and thus prevent massive gel invasion into the matrix. This study advances the current pore scale studies (a single particle passing through a single channel) to Darcy-scale characterization.

Effect of creep on corrosion-induced cracking

Corrosion-induced cracking is the most widely encountered and studied long-term deterioration process in reinforced concrete. Naturally occurring corrosion rates are so low that rust accumulates often over tens of years near the surface of the reinforcement bars before sufficient pressure in the surrounding concrete is generated to induce cracking in the concrete cover. To speed up the process in laboratory tests, corrosion setups with impressed currents have been developed in which the corrosion rate is controlled to be so high that cracking of the concrete cover occurs within a few days. Extrapolating the results of these accelerated tests to those of naturally occurring corrosion requires an understanding of the influence of long-term creep deformations of concrete on the corrosion-induced cracking process. In mathematical models in the literature, creep deformations are often ignored for accelerated but considered for natural corrosion rates in the form of an effective modulus.In this work, three numerical models of increasing complexity are proposed with the aim to investigate the effect of creep on corrosion-induced cracking. The simplest approach is based on an uncracked axis-symmetric thick-walled cylinder combined with a plastic limit on the radial pressure-induced by the accumulation of rust. The model with intermediate complexity comprises a thick-walled cylinder model divided into an inner cracked and an outer uncracked layer. The most comprehensive model consists of a thick-walled cylinder discretised by a three-dimensional lattice approach. Basic creep is predicted in all three approaches by means of the B3 model developed by Bažant and co-workers. Time dependence of strength of concrete is modelled using fib Model Code expressions. It is shown that for the comprehensive lattice model, creep has limited influence on critical corrosion penetration, which indicates that the dependence of the critical corrosion penetration on corrosion rate must have other sources.

Study of Impact Characteristics of ZrO2 Ceramic Composite Projectiles on Ceramic Composite Armor.

Exploring new armor-piercing materials is crucial for improving the penetrative ability of projectiles. Based on the process of in situ solidification injection molding through ceramic dispersant hydrolytic degradation, a ZrO2 ceramic material suitable for use as the tip of a 12.7 mm kinetic energy (KE) projectile was prepared. The ZrO2 ceramic tip can be matched with the metal core of a conventional projectile to form a ceramic composite projectile, increasing the damage to the Al2O3 ceramic composite armor. Specifically, the ZrO2 ceramic tip can increase the impact load on the Al2O3 ceramic panel, prolonging the pre-damage phase and reducing the stable penetration phase, shortening the mass erosion time of the metal core compared with a 12.7 mm metal KE projectile tip. The ceramic composite projectile with the ZrO2 ceramic tip has a lower critical penetration velocity than a 12.7 mm metal KE projectile for Al2O3 ceramic composite armor. Furthermore, the residual velocity, residual length, and residual mass of the metal core of the ceramic composite projectile that penetrated the Al2O3 ceramic composite armor are greater than those of a 12.7 mm metal KE projectile.

Experimental and first-principles studies on superconductivity in noncentrosymmetric La3Se4

We report the synthesis and detailed characterization of superconducting ${\mathrm{La}}_{3}{\mathrm{Se}}_{4}$, with ${T}_{c}\ensuremath{\sim}8.5\ifmmode\pm\else\textpm\fi{}0.1$ K, using x-ray diffraction, electrical transport, magnetization, and heat capacity measurements. ${\mathrm{La}}_{3}{\mathrm{Se}}_{4}$ crystallizes in the noncentrosymmetric cubic ${\mathrm{Th}}_{3}{\mathrm{P}}_{4}$-type structure with space group $I\overline{4}3d$. Characteristic superconducting parameters such as the lower critical field, upper critical field, thermodynamic critical field, coherence length, penetration depth, and Ginzburg-Landau parameter have been determined. The specific heat jump at ${T}_{c}$, $\mathrm{\ensuremath{\Delta}}C/\ensuremath{\gamma}{T}_{c}=2.04\ifmmode\pm\else\textpm\fi{}0.05$, exceeds the value for a weakly coupled BCS superconductor, and the electron-phonon coupling constant is found to be ${\ensuremath{\lambda}}_{ep}=0.87\ifmmode\pm\else\textpm\fi{}0.02$, suggesting superconductivity in ${\mathrm{La}}_{3}{\mathrm{Se}}_{4}$ is in the strong-coupling regime. The estimated upper critical field is well below the calculated Pauli limit, and the Maki parameter value ($\ensuremath{\alpha}&lt;$ 1) indicates that the superconducting upper critical field is dominated by orbital pair breaking. From density functional theory based first-principles simulations we observe the number of states at the Fermi energy is dominated mainly by $d$ and $f$ electrons of La. Furthermore, we observe band crossings along the high-symmetry $k$ lines in the vicinity of the Fermi energy. These bands are observed to split due to the removal of spin degeneracy associated with spin-orbit coupling, with the splitting energy ${E}_{\mathrm{ASOC}}\ensuremath{\approx}$ 65 meV.

Dynamic molten pool behavior of pulsed gas tungsten arc welding with filler wire in horizontal position and its characterization based on arc voltage

To explore the dynamic behavior of molten pool and to find the electric characteristic signals reflecting the weld penetration states and degree for the fixed-point wire-filled pulsed gas tungsten arc welding (GTAW-P) of thin pipes in 2G position, molten pool images from different directions and arc voltage were sensed. During a peak current period, critical penetration occurred, with the molten pool behavior that the topside molten pool height collapsed sharply and was approximately 0.5 mm, and then rose to approximately 1.5 mm during the next base current period. With the increase in backside molten pool width, the oscillation amplitude and frequency of topside molten pool during the base current period increased and decreased, respectively. The oscillation amplitude reached the maximum when over penetration occurred. Such molten pool behaviors could be extracted from the arc voltage signals. The change in average peak voltage (ΔU⁎) could reflect the occurrence of critical penetration. The average base voltage (Ub¯) and the fluctuation of base voltage (ΔUb) increased linearly with the increase in backside molten pool width, which are reliable characteristic signals for the weld penetration degree. The effects of wire filling and base current on the dynamic molten pool behavior and characteristic signals were investigated. Experimental results showed when the base current is 10 A ̶15 A, Ub¯ and ΔUb can effectively characterize the weld penetration degree.

Contact resistance, coupling and hysteresis loss measurements of ITER poloidal field joint in parallel applied magnetic field

The inter-strand contact resistance and AC losses were measured on an International Thermonuclear Experimental Reactor (ITER) poloidal field (PF) coil joint in a parallel applied AC magnetic field. In addition, the hysteresis loss was measured as a function of the angle with the applied magnetic field on a niobium-titanium (NbTi) strand of the same type as in the joint with a vibrating sample magnetometer. The AC loss measurements were performed at four applied field conditions for combinations of 0 or 1 T offset field and 0.2 or 0.4 T sinusoidal amplitude. The hysteresis loss of the joint was compared with the measured AC loss density of the NbTi strand for the same field conditions as the joint AC loss measurement but with varying the angle of the applied field. The subsequent cable twist angles affect the hysteresis loss since the critical current and penetration field depend on the angle of the applied field. It is found that 15.5° is an effective angle for the calculation of the hysteresis loss of joint when compared to the single strand measurement. The inter-strand contact resistance measurements cover all the typical strand combinations from the five cabling stages of the individual conductors, as well as the strand combinations across the two conductors to characterize the inter-strand including the copper sole resistivity. It is the first time to measure the contact resistances and AC losses of the full-size ITER PF joint. By comparing the measured and simulated data in the JackPot-ACDC model, it is also the first time to obtain the accurate inter-strand, inter-petal and strand to copper sole contact resistivities, which are the main input parameters for the further quantitative numerical analysis of the PF joints, in any current and magnetic field conditions.

The Relationship between Bond Strength and Critical Penetration Depth of Rust in Reinforced Concrete Structures

Bond strength and critical penetration depth of rust are major factors that affect the service life of reinforced concrete structures. This research endevoured to establish a relationship between the bond strength and critical penetration depth of rust for reinforced concrete structures. There are 7 brands of Cem 1 cement in Kenya available for use in concrete structures. To achieve the desired objective, three Cem 1 cement brands (Cem A, B and C), fine aggregates, coarse aggregates and steel were obtained from the local Kenyan market. The chemical and physical properties of the materials were investigated. For a selected design strength of 25N/mm2, concrete materials were batched by weight and mixed by an electric pan mixer. For each brand of cement 9 cubes of size 150mm * 150mm * 150mm for a compression test, 9 cylinders of 150mm * 300mm for tensile strength and 9 cylinders of 150mm * 300mm for bond strength were cast. After 24 hours, the cast specimens were demoulded and immersed in curing tanks for 27 days. Specimens for compression, split tensile and bond strength were tested at 7,14 and 28 days. From the results, it was observed that the chemical composition of Cem 1 brands in the Kenyan market vary, which affects the hardening properties of concrete. A model for the critical penetration depth of rust in reinforced concrete was proposed by establishing a correlation between the spilt tensile and bond strength and substituting it in the Xu and Shayan model. The proposed and published models compared well. From the proposed model, a relationship between the critical penetration depth and bond strength was established. It was noted that the critical penetration depth increased with an increase in the bond strength of reinforced concrete. The results of this research are expected to contribute to the modeling of the service life of reinforced concrete structures.

Understanding the geography of trauma: Combining spatial analysis and funnel plots to create comprehensive spatial injury profiles

Understanding geographic patterns of injury is essential to operating an effective trauma system and targeting injury prevention. Choropleth maps are helpful in showing spatial relationships but are unable to provide estimates of spread or degrees of confidence. Funnel plots overcome this issue and are a recommended graphical aid for comparisons that allow quantification of precision. The purpose of this project was to demonstrate the complementary roles of choropleth maps and funnel plots in providing a thorough representation of geographic trauma data. This is a retrospective analysis of emergency medical service transport data of adult patients in Alabama from July 2015 to June 2020. Choropleth maps of case volume and observed-to-expected ratios of incidence were created using US Census Bureau data. Funnel plots were created to relate incidence rate to county population. Subgroup analyses included patients with critical physiology, penetrating, blunt, and burn injuries. We identified 65,247 trauma incidents during the study period. The overall statewide incidence rate was 133 per 10,000 persons. The highest number of incidents occurred in the most populous counties (Jefferson, 10,768; Mobile, 5,642). Choropleth maps for overall incidence and subgroups highlighted that spatial distribution of overall case volume and observed-to-expected ratios are not always congruent. Funnel plots identified possible and probable outliers, and revealed skewed or otherwise unique patterns among injury subgroups. This study demonstrates the complementarity of choropleth maps and funnel plots in describing trauma patterns. Comprehensive geospatial analyses may help guide a data-driven approach to trauma system optimization and injury prevention. Combining maps of case counts, incidence, and funnel plots helps to not only identify geographic trends in data but also quantify outliers and display how far results fall outside the expected range. The combination of these tools provides a more comprehensive geospatial analysis than either tool could provide on its own. Prognostic and Epidemiologic; Level IV.

Impacts of Autonomous Vehicles on Traffic Flow Characteristics under Mixed Traffic Environment: Future Perspectives

Vehicle automation and communication technologies are considered promising approaches to improve operational driving behavior. The expected gradual implementation of autonomous vehicles (AVs) shortly will cause unique impacts on the traffic flow characteristics. This paper focuses on reviewing the expected impacts under a mixed traffic environment of AVs and regular vehicles (RVs) considering different AV characteristics. The paper includes a policy implication discussion for possible actual future practice and research interests. The AV implementation has positive impacts on the traffic flow, such as improved traffic capacity and stability. However, the impact depends on the factors including penetration rate of the AVs, characteristics, and operational settings of the AVs, traffic volume level, and human driving behavior. The critical penetration rate, which has a high potential to improve traffic characteristics, was higher than 40%. AV’s intelligent control of operational driving is a function of its operational settings, mainly car-following modeling. Different adjustments of these settings may improve some traffic flow parameters and may deteriorate others. The position and distribution of AVs and the type of their leading or following vehicles may play a role in maximizing their impacts.

Optimal Planning of a Distribution Network in Egypt

Distribution networks planning is a very complex task as it involves the consideration of various important issues. A model for optimal planning of a distribution network is presented in detail, using Distributed Generation (DG). This paper presented a detailed analysis of the West Delta Network (WDN) as a part of the Egyptian distribution network with a 30% increase in system loading. An Oscillatory Particle Swarm Optimization (OPSO) technique was used to find the optimal locations and sizes of one DG or multiple DGs for achieving the objectives of minimizing total active power losses and system voltage regulation as a single-and-multi-objective optimization problem in a distribution network. Several penetration scenarios have done to evaluate concentrated (at one location) and distributed DGs (at different locations). The results are presented in a comparative form and thoroughly discussed. The obtained results will help in system operation with DG integration and identifying the critical penetration levels for the studied system.

Analysis of highway performance under mixed connected and regular vehicle environment

Purpose This study aims to study the connected vehicle (CV) impact on highway operational performance under a mixed CV and regular vehicle (RV) environment. Design/methodology/approach The authors implemented a mixed traffic flow model, along with a CV speed control model, in the simulation environment. According to the different traffic characteristics between CVs and RVs, this research first analyzed how the operation of CVs can affect highway capacity under both one-lane and multi-lane cases. A hypothesis was then made that there shall exist a critical CV penetration rate that can significantly show the benefit of CV to the overall traffic. To prove this concept, this study simulated the mixed traffic pattern under various conditions. Findings The results of this research revealed that performing optimal speed control to CVs will concurrently benefit RVs by improving highway capacity. Furthermore, a critical CV penetration rate should exist at a specified traffic demand level, which can significantly reduce the speed difference between RVs and CVs. The results offer effective insight to understand the potential impacts of different CV penetration rates on highway operation performance. Originality/value This approach assumes that there shall exist a critical CV penetration rate that can maximize the benefits of CV implementations. CV penetration rate (the proportion of CVs in mixed traffic) is the key factor affecting the impacts of CV on freeway operational performance. The evaluation criteria for freeway operational performance are using average travel time under different given traffic demand patterns.