Development of User-Friendly Web-Based Lost and Found System

People get lost every day, which is a very common incidence in our society. In particular, children, the elderly and mentally challenged people go missing all the time. This paper presents the development of web applications that can provide information and services to both a lost person’s near and dear ones and also people who find the lost person. Using this developed web application, people who have lost a near and dear one can register via their email address and post all the information about the missing person, including photos, in the lost section. People who find someone can also register via their email addresses and post all the information about the found person, including photos, in the found section. There is a search panel where people can search for a lost or found person using their name, age, height, location, skin color, etc. There is also a contact system which can be used to contact the person who has lost or found someone via phone, email, or by connecting with their social media profile. Nowadays, when people lose someone or find someone, they report it to the police, advertise on television or in newspapers, and post it on all social media sites like Facebook and WhatsApp. But this web application provides a faster and enhanced way to find and connect with lost and found people.

Lost and Found

It's a green bag. I put my tennis racket in it. I lost my backpack. It's a blue and white one with a pair of sunglasses in it.

Lost and Found:For Free or For a Fee?

Recently,a company dealing in lost-and-found property started up in Nanjing. Company employees say lost property is sent to the company by finders such as dustmen, who can receive 30 percent of a finder’s fee.

Effects of mechanical vibration on filling and solidification behavior, microstructure and performance of Al/Mg bimetal by lost foam compound casting

Al/Mg bimetal was prepared by lost foam solid-liquid compound casting,and the effects of mechanical vibration on the filling and solidification behavior,microstructure and performance of the bimetal were investigated.Results show that the mechanical vibration has a remarkable influence on the filling and solidification processes.It is found that after mechanical vibration,the filling rate increases and the filling rate at different times is more uniform than that without vibration.In addition,the mechanical vibration also increases the wettability between liquid AZ91D and A356 inlays.The mechanical vibration reduces the horizontal and vertical temperature gradient of the casting and makes the temperature distribution of the whole casting more uniform.Compared to the Al/Mg bimetal without vibration,the shear strength is improved by 39.76%after the mechanical vibration is applied,due to the decrease of the inclusions and Al_(12)Mg_(17) dendrites,and the refinement and uniform distribution of the Mg_(2)Si particles in the interface of the Al/Mg bimetal.

Machine learning for carbonate formation drilling: Mud loss prediction using seismic attributes and mud loss records

Due to the complexity and variability of carbonate formation leakage zones, lost circulation prediction and control is one of the major challenges of carbonate drilling. It raises well-control risks and production expenses. This research utilizes the H oilfield as an example, employs seismic features to analyze mud loss prediction, and produces a complete set of pre-drilling mud loss prediction solutions. Firstly, 16seismic attributes are calculated based on the post-stack seismic data, and the mud loss rate per unit footage is specified. The sample set is constructed by extracting each attribute from the seismic trace surrounding 15 typical wells, with a ratio of 8:2 between the training set and the test set. With the calibration results for mud loss rate per unit footage, the nonlinear mapping relationship between seismic attributes and mud loss rate per unit size is established using the mixed density network model.Then, the influence of the number of sub-Gausses and the uncertainty coefficient on the model's prediction is evaluated. Finally, the model is used in conjunction with downhole drilling conditions to assess the risk of mud loss in various layers and along the wellbore trajectory. The study demonstrates that the mean relative errors of the model for training data and test data are 6.9% and 7.5%, respectively, and that R2is 90% and 88%, respectively, for training data and test data. The accuracy and efficacy of mud loss prediction may be greatly enhanced by combining 16 seismic attributes with the mud loss rate per unit footage and applying machine learning methods. The mud loss prediction model based on the MDN model can not only predict the mud loss rate but also objectively evaluate the prediction based on the quality of the data and the model.

Clinical efficacy and safety of kyphoplasty for the treatment of osteoporotic vertebral compression fractures at different surgical timings based on the theory of“dynamic-static integration”

Objective:To investigate the clinical efficacy and safety of percutaneous kyphoplasty at different surgical timings in the treatment of osteoporotic vertebral compression fracture(OVCF)based on the theory of“dynamic-static integration”.Methods:Patients with OVCF who underwent percutaneous kyphoplasty in our hospital were selected and divided into Groups A,B,and C for those undergoing surgery within 7,7—21,and>21 days of fracture occurrence.The variations in the amount of bone cement injected,pre-and post-operative pain levels,functional activity,deformity correction of the injured vertebrae,bone cement leakage,and vertebral body height loss were compared among the three groups.Results:Regarding pain relief and functional activity,the postoperative Visual Analog Scale and Oswestry Disability Index scores of the three groups significantly improved.Furthermore,the deformities of the injured vertebrae in the three groups were significantly corrected,with Groups A and B exhibiting superior correction compared to Group C.Moreover,the bone cement leakage rates in groups A and C were higher than that in Group B.At the 3-month follow-up,the loss of vertebral height in Group C was significantly higher than those in groups A and B.Conclusion:Kyphoplasty is effective for OVCF treatment.Early surgery can effectively restore the vertebral height of the injured vertebra,reduce kyphosis,and reduce height loss of the injured vertebra after surgery;nevertheless,treatment within 1—3 weeks of the fracture can reduce the occurrence of bone cement leakage,making the surgery safer.Therefore,surgical treatment within 1—3 weeks of fracture is safer and can achieve satisfactory therapeutic effects.From the perspective of traditional Chinese medicine,PKP surgery can transform the fracture end from a micromotion state to a fixed state,which fully embodies the theory of“dynamic-static integration”.

The Lost Generation and its significance to American Culture

The Lost Generation is actually a group of American writers who were rebelling against what America had become by the 1900s.The Lost generation tendency and Lost generation writers are of great importance to the American and world literature.This article serves as a brief introduction to the Lost generation and its significant writers.

Status quo and development trend of lost foam casting technology

Lost foam casting(LFC)technology has been widely applied to cast iron and cast steel.However,the development of LFC for Al and Mg alloys was relatively slower than that for cast iron and cast steel.The application of LFC to Al and Mg alloys needs more effort,especially in China.In this paper,the development history of LFC is reviewed,and the application situations of LFC to Al and Mg alloys are mainly discussed.Meanwhile,the key problems of LFC for Al and Mg alloys are also pointed out.Finally,the prospects for LFC technology are discussed,and some special new LFC technologies are introduced for casting Al and Mg alloys.In future,the development trends of green LFC technology mainly focus on the special new LFC methods,metal material,coating,heat treatment,new foam materials as well as purification technology of tail gas,etc.

Effect of vibration frequency on microstructure and performance of high chromium cast iron prepared by lost foam casting

In the present research, high chromium cast irons(HCCIs) were prepared using the lost foam casting(LFC) process. To improve the wear resistance of the high chromium cast irons(HCCIs), mechanical vibration was employed during the solidification of the HCCIs. The effects of vibration frequency on the microstructure and performance of the HCCIs under as-cast, as-quenched and as-tempered conditions were investigated. The results indicated that the microstructures of the LFC-produced HCCIs were refined due to the introduction of mechanical vibration, and the hardness was improved compared to that of the alloy without vibration. However, only a slight improvement in hardness was found in spite of the increase of vibration frequency. In contrast, the impact toughness of the as-tempered HCCIs increased with an increase in the vibration frequency. In addition, the wear resistance of the HCCIs was improved as a result of the introduction of vibration and increased with an increase in the vibration frequency.

Effect of vibration frequency on primary phase and properties of grey cast iron fabricated by lost foam casting

The properties of gray cast iron(GCI)are affected by density of matrix,size of flake graphite and primary austenite.In this paper,the Y-type specimen of GCI was prepared by lost foam casting(LFC)with and without vibration,and the influence of vibration frequency on the density of matrix,size of primary phase,and properties of the GCI was studied.The results show that the length of the flake graphite and the size of the primary austenite in GCI firstly decrease and then increase with the increase of the vibration frequency.With a vibration frequency of 35 Hz,the length of the flake graphite is the shortest,the primary austenite is the finest and the density of the matrix is the highest.In addition,the tensile strength,elongation and hardness of the GCI firstly increase and then decrease with the increase of the vibration frequency,due to the refinement of the primary phase and the increase of the matrix density.In order to analyze the refinement mechanism of the primary phase of the GCI fabricated by the LFC with vibration,the solidification temperature fields of the GCI fabricated by the LFC with the vibration frequency of 0 and 35 Hz were measured.The results show that the vibration reduces the eutectic point of the GCI and increases the supercooling degree during the eutectic transformation.As a result,the length of the flake graphite and the size of the primary austenite in GCI fabricated by LFC with the vibration frequency of 35 Hz decrease.

Research progress and prospect of plugging technologies for fractured formation with severe lost circulation

By reviewing the mechanisms of drilling fluid lost circulation and its control in fractured formations, the applicability and working mechanisms of different kinds of lost circulation materials in plugging fractured formations have been summarized. Meanwhile, based on the types of lost circulation materials, the advantages, disadvantages, and application effects of corresponding plugging technologies have been analyzed to sort out the key problems existing in the current lost circulation control technologies. On this basis, the development direction of plugging technology for severe loss have been pointed out. It is suggested that that the lost circulation control technology should combine different disciplines such as geology, engineering and materials to realize integration, intelligence and systematization in the future. Five research aspects should be focused on:(1) the study on mechanisms of drilling fluid lost circulation and its control to provide basis for scientific selection of lost circulation material formulas, control methods and processes;(2) the research and development of self-adaptive lost circulation materials to improve the matching relationship between lost control materials and fracture scales;(3) the research and development of lost circulation materials with strong retention and strong filling in three-dimensional fracture space, to enhance the retention and filling capacities of materials in fractures and improve the lost circulation control effect;(4) the research and development of lost circulation materials with high temperature tolerance, to ensure the long-term plugging effect of deep high-temperature formations;(5) the study on digital and intelligent lost circulation control technology, to promote the development of lost circulation control technology to digital and intelligent direction.

Preparation and properties of magnesium oxysulfate cement and its application as lost circulation materials

Loss of drilling fluids in large porous and fractured zones inevitably up-regulates the overall cost of drilling.As a type of acid-soluble cement,magnesium oxysulfate(MOS)cement is arousing huge attention for the less hygroscopic nature and less damaging to steel casings compared with magnesium oxychloride(MOC)cement.The present study developed MOS cement as a fast setting,high strength and acid-soluble lost circulation material to reduce the problem of losses.As suggested in this study,a higher strength of MOS cement at 70℃could be achieved by elevating M_(g)O/MgSO_(4)·7 H_(2)O molar ratio or downregulating H_(2)O/MgSO_(4)·7 H_(2)O molar ratio.Boric acid and borax could act as effective retarders.Plugging slurry based on MOS cement could effectively block the simulated porous loss zones exhibiting a diameter from 1.24 mm to 1.55 mm,as well as the fractured loss zones with a width from 2 mm to 5 mm and bearing a pressure difference up to 8 MPa.Permeability recovery test demonstrated that it facilitated future oil and gas production.The successful field application in the Junggar Basin,Xinjiang,China verified the significant plugging effect of MOS cement for severe loss problems.

Plugging performance and mechanism of an oil-absorbing gel for lost circulation control while drilling in fractured formations

Lost circulation of drilling fluid is one of the most common engineering problems in the drilling process of fractured formations.In this study,an oil-absorbing polymer gel synthesized using compound monomers with rigid and flexible chains was applied to control the oil-based drilling fluid loss while drilling.The microstructure,oil-absorbing performance,and plugging performance the gel was investigated.A large number of dense pores on the surface of the gel were observed,which allowed the oil molecules to enter the internal space of the gel.The initial oil absorption capacity of the gel was fast,and it increased with the increase in the temperature and decrease in the particle size,reaching 20.93 g/g at140℃.At a high temperature of 140℃,the bearing pressure capacity of the gel formula containing particles of different particle sizes reached 7.6 MPa for a fracture of a width of 3 mm,showing that the oil-absorbing gel have excellent plugging performance at high temperature.Plugging mechanism of the gel was investigated through visualized fracture plugging experiments.Results show that the dynamic migratio n,particle-swelling,particle-bridging,particle-aggregation,deformation-filling,and compaction-plugging contribute to the whole lost circulation control process,reflecting that the plugging performance can be effectively enhanced by improving the aggregation and filling degrees of the gel with different particle sizes.

Simulation and experimental study on the surface morphology and energy lost of the target material under non-overlapping impact of angular particles

In order to further understand the effect of solid impurities on pipeline wall during erosion,the particle impact process without fluid was extracted for specific study.The effect of multi-impact particles on the wall of pipeline was studied experimentally and simulated.In this experiment,an improved ejection apparatus was implemented to carry out multi-impacts non-overlapping impingement by rhombic particles made of high speed steel(W18Cr4V)on the AA6061 aluminum alloy plate through changing particle angle,incident angle,orientation angle and impact velocity.As a result,each particle's penetration depth was investigated and particles' rebound trajectory can be described through this experiment as well as surface morphology of the target material after impingement.The ductile damage criterion,shear damage criterion and MSFLD damage criterion were jointly implemented in ABAQUS/CAE software to simulate the whole process of collision which proved to be effective by getting consistent result compared with experimental data.It is found that under the condition of continuous non-overlapping impact,the target material produces a small work hardening effect in the impact area by converting kinetic energy of moving particles into internal energy of plate so as to reduce the penetration depth of each impact particle.

Structural failure mechanism and strengthening method of fracture plugging zone for lost circulation control in deep naturally fractured reservoirs

Focused on the lost circulation control in deep naturally fractured reservoirs, the multiscale structure of fracture plugging zone is proposed based on the theory of granular matter mechanics, and the structural failure pattern of plugging zone is developed to reveal the plugging zone failure mechanisms in deep, high temperature, high pressure, and high in-situ stress environment. Based on the fracture plugging zone strength model, key performance parameters are determined for the optimal selection of loss control material(LCM). Laboratory fracture plugging experiments with new LCM are carried out to evaluate the effect of the key performance parameters of LCM on fracture plugging quality. LCM selection strategy for fractured reservoirs is developed. The results show that the force chain formed by LCMs determines the pressure stabilization of macro-scale fracture plugging zone. Friction failure and shear failure are the two major failure patterns of fracture plugging zone. The strength of force chain depends on the performance of micro-scale LCM, and the LCM key performance parameters include particle size distribution, fiber aspect ratio, friction coefficient, compressive strength, soluble ability and high temperature resistance. Results of lab experiments and field test show that lost circulation control quality can be effectively improved with the optimal material selection based on the extracted key performance parameters of LCMs.

Modeling of Mold Filling and Solidification in Lost Foam Casting

Based on the characteristics of the lost foam casting (LFC) and the artificial neural network technique, a mathematical model for the simulation of the melt-pattern interface movement during the mold filling of LFC has been proposed and experimentally verified. The simulation results are consistent with the experiments in both the shapes of melt front and filling sequences. According to the calculated interface locations, the fluid flow and the temperature distributions during the mold filling and solidification processes were calculated, and the shrinkage defect of a lost foam ductile iron casting was predicted by considering the mold wall movement in LFC. The simulation method was applied to optimize the casting design of lost foam ductile iron castings. It is shown that the model can be used for the defects prediction and for casting design optimization in the practical LFC production.

Lost circulation material for abnormally high temperature and pressure fractured-vuggy carbonate reservoirs in Tazhong block, Tarim Basin, NW China

To effectively solve the problem of lost circulation and well kick frequently occurring during the drilling of abnormally high temperature and pressure fractured-vuggy reservoirs in the Tazhong block, a rigid particle material, GZD, with high temperature tolerance, high rigidity(> 8 MPa) and low abrasiveness has been selected based on geological characteristics of the theft zones in the reservoirs. Through static pressure sealing experiments, its dosage when used alone and when used in combination with lignin fiber, elastic material SQD-98 and calcium carbonate were optimized, and the formula of a new type(SXM-I) of compound lost circulation material with high temperature tolerance and high strength was formed. Its performance was evaluated by compatibility test, static sealing experiment and sand bed plugging experiment. The test results show that it has good compatibility with drilling fluid used commonly and is able to plug fractures and vugs, the sealed fractures are able to withstand the static pressure of more than 9 MPa and the cumulative leakage is 13.4 mL. The mud filtrate invasion depth is only 2.5 cm in 30 min when the sand bed is made of particles with sizes between 10 mesh and 20 mesh. Overall, with good sealing property and high temperature and high pressure tolerance, the lost circulation material provides strong technical support for the safety drilling in the block.

EFFECT OF La-RICH RE ON THE STRUCTURE AND PROPERTIES OF B319 ALLOY IN LOST FOAM CASTING

By use of ICP spectroscopy, energy spectrum analysis, hydrogen tester, image analyzer, the differential scanning calorimetric(DSC) and microscope analysis, the effects of RE on the Porosity, structure and properties of B319 aluminum alloy were studied. The results show that under the 0.3 °C /s slow cooling rate in lost foam casting, the effect of RE on modification and grain size of B319 aluminum alloy is little. With the increase of RE master alloy, the tensile strength and elongation increase. When RE>0.15%, block like La 2Si 2Al 3 phase appear, and the tensile strength and elongation decrease. The results also show that the melt hydrogen content and casting porosity can be decreased greatly by adding 0.15% RE to aluminum melt. This is the important reason why RE improves the mechanical properties of casting under lost foam casting condition.

Microstructure and mechanical properties of lost foam cast 356 alloys

Microstructure and mechanical properties of lost foam cast aluminum alloys have been investigated in both primary A356(0.13% Fe) and secondary 356(0.47%). As expected, secondary 356 shows much higher content of Fe-rich intermetallic phases, and in particular the porosity in comparison with primary A356. The average area percent and size(length) of Fe-rich intermetallics change from about 0.5% and 6 μm in A356 to 2% and 25 μm in 356 alloy. The average area percent and maximum size of porosity also increase from about 0.4% and 420 μm to 1.4% and 600 μm, respectively. As a result, tensile ductility decreases about 60% and ultimate tensile strength declines about 8%. Lower fatigue strength was also experienced in the secondary 356 alloy. Low cycle fatigue(LCF) strength decreased from 187 MPa in A356 to 159 MPa in 356 and high cycle fatigue(HCF) strength also declined slightly from 68 MPa to 64 MPa.

Effects of Parameters on Formation and Microstructure of Surface Composite Layer Prepared by Lost Foam Casting Technique

Surface composite layer was fabricated on the AZ91D substrate using the lost foam casting （LFC） process. The pre-coating layer reacted with melt substrate and formed the composite layer, and the coating was mainly consist of alloying aluminum powder and low-temperature glass powder （PbO-ZnO-Na20）. The vacuum degree, pouring temperature, mold filling process of melt, and pre-coating thickness played an important role during the formation process of composite layer. The results show that surface morphology of composite layer can be divided into three categories： alloying effect of bad and good ceramic layer, alloying effect of good and bad ceramic layer, composite layer of good quality. The main reason for bad alloying layer is that alloying pre-coating thickness is so thin that it is scoured easily and involved in the melt, in addition, it is difficult for melt to infiltrate into the alloying coating owing to the surface tension of coating when the vacuum degree is excessively low. Bad ceramic layer is because of somewhat lower pouring temperature and the thicker alloying coating, due to the absorption of heat from the melt, making low temperature glass powder pre-coating layer fuse inadequate. Thus, to get good quality composite layer, the process conditions must be appropriate, the result shows that the optimum process parameters are as follows： at a pouring temperature of 800 ~C, vacuum degree of -0.06 MPa, alloying pre-coating thickness ofO.4 mm, and low glass powder pre-coating layer thickness ofl mm.