Gyikoo/KT_QA huggingface dataset:
问题：As the circuit shown in the following figure,C1=4μF, it has been charged tou1=120V. Connect it toR−C2series circuit (C2hasn’t been charged),R=1kΩ,C2=2μF. Find the following values at t = 0.001s: (1) The voltage of capacitorC1isu1(0.001)=[填空1]V; (2) The voltage of capacitorC2isu2(0.001)=[填空2]V; (3) The current flow through resistor R isi(0.001)=[填空3]A.
答案：{"1": ["98.9"], "3": ["0.0567"], "2": ["42.2"]}
问题：As the circuit shown in Fig.9-4, the characteristic of two special MOSFET is whenuGS&lt;1V, between D and S is open and whenuGS&gt;1V, there’s a resistorRONbetween D and S. In fact, there’s a parasitic capacitor between G and S andCGS=10pF.RON=100Ω,RL=10kΩ,US=5Vand the waveform of input voltageuINis shown in the figure. Solve: (1) Att=0.5μs,uINchanges from ‘1’ to ‘0’. After the transfer delay=[填空1]ns,uOUTchanges from ‘1’ to ‘0’; (2) Att=1μs,uINchanges from ‘0’ to ‘1’. After the transfer delay=[填空2]ns,uOUTchanges from ‘0’ to ‘1’.
答案：{"1": ["22.3"], "2": ["1.61"]}
问题：Multiple selection problem (one option)For the circuit, which of the following characteristics is correct? {'A': 'over-damping.', 'B': 'critical-damping.', 'C': 'under-damping.', 'D': 'no-damping'}
答案：C
问题：Multiple selection problem (single option)As to the speed of the energy transfer, which of the following type is the fastest? {'A': 'under-damping.', 'B': 'critical-damping.', 'C': 'over-damping.'}
答案：A
问题：Multiple selection problem (one option)Suppose the second-order RLC serial circuit is under critical-damping condition, larger L will cause it changing into what type? {'A': 'over-damping.', 'B': 'critical-damping.', 'C': 'under-damping.'}
答案：C
问题：Fill in the blankFor the second-order ODEd2xdt2+6dxdt+8x=0, we know one of its two characteristic roots isλ1=−2. The other root isλ2=[填空1].
答案：{"1": ["-4"]}
问题：Fill in the blankFor the second-order ODEd2xdt2+4dxdt+8x=0, its conjugate complex characteristic roots areλ1,2=A±jB. A=[填空1], B=[填空2].
答案：{"1": ["-2"], "2": ["2"]}
问题：Fill in the blankFor the circuit, its characteristic equation isλ2+Aλ+B=0. A=[填空1], B=[填空2].
答案：{"1": ["125"], "2": ["2500"]}
问题：Fill in the blank and multiple selection (single option)For the second-order RLC parallel, its attenuation factor $alpha {rm{ = }}_____$, free oscillating frequency ${omega _{rm{0}}}{rm{ = }}_____$. Which of the following characteristics is right for the circuit? {'A': 'over-damping.', 'B': 'critical-damping.', 'C': 'under-damping.', 'D': 'no-damping'}
答案：C
问题：As the circuit shown in Fig. 10-1,【1】its characteristic roots arep1=[填空1],p2=[填空2].
答案：{"1": ["-0.367"], "2": ["-3.63"]}
问题：Select the characteristic of the transient process is: {'A': 'over-damping', 'B': 'critical-damping', 'C': 'under-damping', 'D': 'no-damping'}
答案：A
问题：As the circuit shown in Fig. 10-2, its attenuation coefficientδ= [填空1] 1/s, and attenuating oscillating angular frequencyω= [填空2]rad/s.
答案：{"1": ["3000"], "2": ["1000"]}
问题：The circuit has no initial energy storage, the switch S is closed at t=0. Find the coefficients A, B, and C in the expression of inductive current after switching:iL(t)=Ae−50t+Be−150t+C.[填空1][填空2][填空3]
答案：{"1": ["-0.3"], "3": ["0.2"], "2": ["0.1"]}
问题：As the circuit shown in Fig. 10-4, we know thatuS1=1V,uS2=2V,R1=2Ω,R2=R3=4Ω,L=56H,C=15F. The switch S is closed at t=0. Find the coefficients A, B, and C in the expression of capacitive voltage:uC(t)=Ae−2t+Be−3t+C.[填空1][填空2][填空3]
答案：{"1": ["-3.75"], "3": ["1"], "2": ["3.75"]}
问题：As the circuit shown in Fig. 10-5, the switch S is opened at t=0. Find the coefficientsK,ω,θin the expression of capacitive voltage .There are two sets of solutions:【Notice: You can EXCHANGE your two sets of solutions if you have the right solutions but it still displays errors.】K1,ω1,θ1(use Degrees, not Radians)[填空1][填空2][填空3]K2,ω2,θ2(use Degrees, not Radians)[填空4][填空5][填空6]
答案：{"1": ["-356"], "3": ["-4.03"], "2": ["139"], "5": ["139"], "4": ["356"], "6": ["176"]}
问题：As the circuit shown in Fig. 10-6, we know that the initial value of inductive currentiL(0)=2A, the initial value of capacitive voltageuC(0)=0,R=50Ω,L=0.5H,C=100μF. Find the coefficientsK,ω,θ,Din the expression of resistive current:iR(t)=Ke−100tsin(ωt+θ)+D.[填空1][填空2][填空3][填空4]K,ω,θ
答案：{"1": ["2"], "3": ["0"], "2": ["100"], "4": ["1"]}
问题：Multiple selection problem (single option)Which of the following expression can be used to express the rms and the phase of a sinusoid at the same time? {'A': 'a real number', 'B': 'a complex number', 'C': 'an imaginary number', 'D': 'a rational number'}
答案：B
问题：Fill in the blankWe know3+j45+j6=A∠B∘. A=[填空1] and B=[填空2].
答案：{"1": ["0.64"], "2": ["2.94"]}
问题：Fill in the blankThe phasor expression of the sinusoidi(t)=155.56sin(376.8t+30∘)isI˙=A∠B∘, where A=[填空1]and B=[填空2]. The frequency of the sinusoid is f=[填空3]Hz.
答案：{"1": ["110"], "3": ["60"], "2": ["30"]}
问题：Fill in the blankFor two sinusoidsi1(t)=2√×110sin(314t+30∘)andi2(t)=2√×220sin(314t+60∘), use the phasor method to calculate their sum, i.e.i1(t)=i1(t)+i2(t)=2√×Asin(314t+B∘), where A=[填空1]and B=[填空2].
答案：{"1": ["320"], "2": ["50"]}
问题：Multiple selection problem(one option)For the circuit,if the frequency of the excitation is f=200Hz, it is {'A': 'resistive', 'B': 'capacitive', 'C': 'inductive'}
答案：B
问题：Multiple selection problem (one option)For the circuit,if the frequency of the excitation is f=100Hz, it is {'A': 'resistive', 'B': 'capacitive', 'C': 'inductive'}
答案：B
问题：Multiple selection problem (one option)For the circuit,if the frequency of the excitation is f=200Hz, it is {'A': 'resistive', 'B': 'capacitive', 'C': 'inductive'}
答案：C
问题：Multiple selection problem(one option)For the circuit,if the frequency of the excitation is f=100Hz, it is {'A': 'resistive', 'B': 'capacitive', 'C': 'inductive'}
答案：C
问题：Fill in the blankThe input impedance of the one-port a-b isZab=A∠B∘Ω. A=[填空1]and B=[填空2].
答案：{"1": ["31.86"], "2": ["35.57"]}
问题：Multiple selection problem (one option)For of the capacitors, if the frequency of the terminal voltage is 50Hz, the frequency of its absorbed instantaneous power is: {'A': '0', 'B': '20Hz', 'C': '50Hz', 'D': '100Hz'}
答案：D
问题：Multiple selection problem(one option)For the first expression of the absorbed instantaneous power of the general one-port network, which of the following is the constant part? {'A': '$UI$', 'B': '$dot Udot I$', 'C': '$UIsin varphi$', 'D': '$UIcos varphi$'}
答案：D
问题：Fill in the blank and single option selectionwhich isthe capacitance required to increase the power factor to 0.9. {'A': 'higher than', 'B': 'lower than', 'C': 'same as'}
答案：A
问题：Fill in the blankFor a capacitor, its rms voltage is 100V and the associated rms current flowing through it is 50A, its received reactive power Q=[填空1]var.
答案：{"1": ["-5000"]}
问题：Fill in the blankFor the one-port network with associated current and voltage directions, its rms voltage is 100V and rms current is 50A. Its received apparent power S=[填空1]VA.
答案：{"1": ["5000"]}
问题：Fill in the blank and single option selectionSuppose f=50Hz, U=380V, the capacitance required to increase the power factor to 0.95 isC=[填空1]μF
答案：{"1": ["443"]}
问题：Multiple selection problem (multiple options)Which of the following options can be regarded as frequency characteristics? {'A': 'port impedance', 'B': 'port admittance', 'C': 'branch variable', 'D': 'transfer function'}
答案：A, B, C, D
问题：For the circuit, suppose RC=2, the angular frequency needs to beω=[填空1]rad/s to ensure the magnitude of the transfer function to be 0.707.
答案：{"1": ["0.5"]}
问题：Fill in the blankThe input magnitude of the circuit isUI=20Vand the output magnitude of the circuit isUO=10V, the decibel value of the network function|H|=[填空1]dB.
答案：{"1": ["-6"]}
问题：Multiple selection problem(single option)Which of the following MOSFET working region is required to be utilized in an amplifier? {'A': 'cut-off region', 'B': 'voltage-controlled resistor region', 'C': 'voltage-controlled current region'}
答案：C
问题：Multiple selection problem(single option)Which of the following description is correct for the high frequency performance of the MOSFET small signal amplifier while considering the parasitic capacitor ${C_{{rm{GS}}}}$? {'A': 'high pass', 'B': 'low pass', 'C': 'band pass', 'D': 'band stop', 'E': 'full pass'}
答案：B
问题：Multiple selection questions(single option)In general magnitude resonant frequency characteristic, wider curve means: {'A': 'Higher quality factor', 'B': 'Lower quality factor', 'C': 'Same quality factor', 'D': 'Doesn’t matter'}
答案：B
问题：For the resonant circuit, its quality factor Q=[填空1].
答案：{"1": ["15.8"]}
问题：For the resonant circuit, its stored electromagnetic energy isWT=[填空1]J  and its consumed energy in the resistor during one period isW=[填空2]mJ. It quality factor is [填空3].
答案：{"1": ["0.025"], "3": ["15.8"], "2": ["9.95"]}
问题：For the resonant circuit, its band width isf2−f1=[填空1]Hz.
答案：{"1": ["318.5"]}
问题：Multiple selection problem(single option)For LC serial resonant circuit, what is the port property when it’s in resonant frequency? {'A': 'open circuit', 'B': 'short circuit', 'C': 'inductive', 'D': 'capacitive'}
答案：B
问题：For LC parallel resonant circuit, what is the port property when it’s in resonant frequency? {'A': 'open circuit', 'B': 'short circuit', 'C': 'inductive', 'D': 'capacitive'}
答案：A
问题：The figure shows four circuits. Answer the following questions.When $omega = {omega _1} = frac{1}{{sqrt {{L_1}{C_1}} }} $, the circuits represent the characteristic of open circuit are shown in Fig ______. {'A': 'a', 'B': 'b', 'C': 'c', 'D': 'd'}
答案：B
问题：For the circuit shown in Fig(c), compare the operating frequency ${omega _{rm{2}}}$ when the circuit represents the characteristic of open circuit with the operating frequency ${omega _{rm{1}}}$ when the circuit represents the characteristic of short circuit. Choose: larger than or less than? {'A': 'larger than', 'B': 'less than'}
答案：B
问题：For the circuit shown in Fig(d), compare the operating frequency ${omega _{rm{2}}}$ when the circuit represents the characteristic of open circuit with the operating frequency ${omega _{rm{1}}}$ when the circuit represents the characteristic of short circuit. Choose: larger than or less than? {'A': 'larger than', 'B': 'less than'}
答案：A
问题：The figure shows four circuits. Answer the following questions.When $omega = {omega _1} = frac{1}{{sqrt {{L_1}{C_1}} }} $, the circuits represent the characteristic of short circuit are shown in Fig ______. {'A': 'a', 'B': 'b', 'C': 'c', 'D': 'd'}
答案：A, C, D
问题：Figure (a) is a practical circuit for the fluorescent lamp, whose equivalent circuit is shown in figure (b). The fluorescent lamp can be regarded as a resistor, and its parameters are 110V, 40W. The ballast is an inductor, the supply voltage is 220V, and the frequency is 50Hz. To ensure that the voltage across modulator tube is 110V. Find:① the currentI=[填空1]A; ② the inductanceLof the ballast=[填空2]H;  ③ the power factorcosφ1of the circuit this moment =[填空3]; ④ if the power factor of the circuit is raised to1, the capacitanceCneed to be connected in parallel=[填空4]μF； ⑤ the reactive powerQCdelivered by the capacitor=[填空5]Var.
答案：{"1": ["0.364"], "3": ["0.5"], "2": ["1.67"], "5": ["69.3"], "4": ["4.56"]}
问题：A 220 V, 50Hz power supply is used for supplying a set of dynamic load, the load currentI=318A, the powerP=42kW. Now we want to connect a set of lighting (incandescent light bulb) with the power of 20kW to the power supply. It need to be connected a parallel capacitor so that the total current is less than 325A after connecting lighting. Find the capacitanceCwe wanted, the reactive powerQCdelivered by the parallel capacitor, and the power factorcosφof the circuit at the moment.C=[填空1]μFQC=[填空2]kVarcosφ=[填空3]
答案：{"1": ["1338"], "3": ["0.867"], "2": ["20.3"]}
问题：The port voltage of RLC serial circuit isuS=102√sin1000tV. When the capacitanceC=10μF, the current in the circuit reaches its maximum value,Imax=2A. Find: the resistanceR=[填空1]Ω the inductanceL=[填空2]H; the quality factor of serial resonant circuitQ=[填空3];  the capacitor voltageUC=[填空4]V, the inductor voltageUL=[填空5]V.
答案：{"1": ["5"], "3": ["20"], "2": ["0.1"], "5": ["200"], "4": ["200"]}
问题：The circuit is shown in the figure. Its resonant frequency isω0[填空1]rad/s,  and the input impedance in resonance state isZ(ω0)[填空2]Ω.
答案：{"1": ["1250"], "2": ["8.33"]}
问题：Find the resonant angular frequencyω0=[填空1]rad/sof the circuit shown in the figure. The given conditions areL=8mHandC=20μF.
答案：{"1": ["5000"]}
问题：As the circuit shown in the figure,U=200V,R1=R2=50Ω,L1=0.2H,L4=0.1H,C2=5μF,C3=10μFthe reading of ammeterA2is zero. Find: the reading of ammeterA4is [填空1]A.
答案：{"1": ["4.12"]}
问题：The circuit shown in the figure has resonance at the excitation frequency f =50Hz. The reading of ammeter is 0.3A, the reading of voltmeter is 20V and the reading of power meter is 8W. Find the value of three elements: (1) the resistanceR=[填空1]Ω; (2) the inductanceL=[填空2]mH; the capacitanceC=[填空3]μF.
答案：{"1": ["32"], "3": ["47.7"], "2": ["76.4"]}
问题：Multiple selection problem(single option)For two linear inductively coupled coils 1 and 2, which of the following description is correct? {'A': '${M_{{rm{12}}}} = {M_{{rm{21}}}}$', 'B': '${M_{{rm{12}}}}$ is bigger.', 'C': '${M_{{rm{21}}}}$ is bigger.', 'D': 'It depends.'}
答案：A
问题：Fill in the blankFor the two inductively coupled coils, supposeL1=2mHandL2=8mH, the possible largest mutual inductance between them isM=[填空1]mH.
答案：{"1": ["4"]}
问题：For the inductive coupling coils in Fig. (a), as the reference directions showed in the figure, the relationship between voltage and current should be:1)$ left{ {begin{array}{*{20}{c}}{{u_1} = {L_1}frac{{{rm{d}}{i_1}}}{{{rm{d}}t}} + Mfrac{{{rm{d}}{i_2}}}{{{rm{d}}t}}}{{u_2} = {L_2}frac{{{rm{d}}{i_2}}}{{{rm{d}}t}} + Mfrac{{{rm{d}}{i_1}}}{{{rm{d}}t}}}end{array}} right.$2)$ left{ {begin{array}{*{20}{c}}{{u_1} = {L_1}frac{{{rm{d}}{i_1}}}{{{rm{d}}t}} - Mfrac{{{rm{d}}{i_2}}}{{{rm{d}}t}}}{{u_2} = -{L_2}frac{{{rm{d}}{i_2}}}{{{rm{d}}t}} - Mfrac{{{rm{d}}{i_1}}}{{{rm{d}}t}}}end{array}} right.$3)$ left{ {begin{array}{*{20}{c}}{{u_1} = {L_1}frac{{{rm{d}}{i_1}}}{{{rm{d}}t}} + Mfrac{{{rm{d}}{i_2}}}{{{rm{d}}t}}}{{u_2} = -{L_2}frac{{{rm{d}}{i_2}}}{{{rm{d}}t}} - Mfrac{{{rm{d}}{i_1}}}{{{rm{d}}t}}}end{array}} right.$4)$ left{ {begin{array}{*{20}{c}}{{u_1} = {L_1}frac{{{rm{d}}{i_1}}}{{{rm{d}}t}} + Mfrac{{{rm{d}}{i_2}}}{{{rm{d}}t}}}{{u_2} = -{L_2}frac{{{rm{d}}{i_2}}}{{{rm{d}}t}} + Mfrac{{{rm{d}}{i_1}}}{{{rm{d}}t}}}end{array}} right.$Your answer is: {'A': '1)', 'B': '2)', 'C': '3)', 'D': '4)'}
答案：C
问题：#Notice# The voltage source in Fig.(b) had the wrong symbol, howerver, it is indeed a voltage source, not a current source.根据本图回答以下（1) （2)题：1) For an ideal transformer in Fig. (a), we know that the number of the turns in the primary side is $ {N_{rm{1}}}$, and the number of the turns in the secondary side is $ {N_{rm{2}}}$, The primary side connects the current source ${dot I_{rm{S}}} $, and the secondary side connects the resistor $R $. If the output power of the secondary side increases, then the turns in the secondary side should be a) increased b) decreased？ {'A': 'increased', 'B': 'Decreased'}
答案：B
问题：（接上题）2) The current source ${dot I_{rm{S}}} $ is changed into the voltage source，as shown in Fig. (b). If the output power of the secondary side increases, then the turns in the secondary side should be a) increased b) decreased？ {'A': 'increased', 'B': 'Decreased'}
答案：A
问题：As the circuit shown in the figure, we know that the current sourceiS=2e−4tA. Find the coefficients A, B, and C in the following expressions.uab=Ae−4t,uac=Be−4tandubc=Ce−4t.Your answer is:A=[填空1]B=[填空2]C=[填空3]
答案：{"1": ["-16"], "3": ["-8"], "2": ["-24"]}
问题：As the circuit shown in the figure,we know thatR=50Ω,L1=70mH,L2=25mH,M=25mH,C=1μF, and the angular frequencyω=104rad/s.Find the input impedanceZ=[填空1]+j[填空2]Ω    of the circuit.
答案：{"1": ["50"], "2": ["450"]}
问题：For the air-core transformer circuit in the figure,we know thatUS=220V,R1=10Ω,ωL1=25Ω,ωM=30Ω,R2=20Ω,ωL2=40Ω.Find:1) the effective value ofI˙1isI1=[填空1]A;2) the effective value ofI˙2isI2=[填空2]A 3) the power supplied by the source isP=[填空3]W.
答案：{"1": ["10.9"], "3": ["2250"], "2": ["7.29"]}
问题：As the circuit shown in the figure, we know thatUS=10V. When the transformation ratio of the ideal transformer isn=[填空1], the load resistance of6Ωwould get the maximum power. And the value isPmax=[填空2]W.
答案：{"1": ["5"], "2": ["0.167"]}
问题：As the circuit shown in the figure, we know thatU˙S=180∠45∘V. Find1) the reading of the voltmeter (effective value) =[填空1]V;2) the reading of the power meter =[填空2]W.
答案：{"1": ["120"], "2": ["0"]}
问题：Multiple selection problem(multiple options)For the signal, which of the following components are included in the Fourier series? {'A': 'dc', 'B': 'even sine', 'C': 'even cosine', 'D': 'odd sine', 'E': 'odd cosine'}
答案：A, D, E
问题：A multiple choice problem presents radio buttons for student input. Students can only select a singleoption presented. Multiple Choice questions have been the subject of many areas of research due to the earlyinvention and adoption of bubble sheets.One of the main elements that goes into a good multiple choice question is the existence of good distractors.That is, each of the alternate responses presented to the student should be the result of a plausible mistakethat a student might make.What Apple device competed with the portable CD player? {'A': 'The iPad', 'B': 'Napster', 'C': 'The iPod', 'D': 'The vegetable peeler'}
答案：C
问题：The connections of two sets of three phase load is shown in the figure. The three phase source is balanced. Line voltage isU˙AB=380∠30oVand the impedance areZ1=100+j60Ω,Z2=50−j80Ω.The value of A phase currentI˙Ais [填空1]A and the phase angle of it is [填空2]degree;The value of B phase currentI˙Bis[填空3]A and the phase angle of it is [填空4]degree;The value of C phase currentI˙Cis [填空5]A and the phase angle of it is [填空6]degree.
答案：{"1": ["7.28"], "3": ["7.28"], "2": ["43"], "5": ["7.28"], "4": ["-77"], "6": ["163"]}
问题：As the circuit shown in the figure, the line voltage of balanced three phase source isU˙AB=380∠30oVand the impedances areZ1=50+j50Ω，ZA=ZB=ZC=50+j100Ω.The value of A phase currentI˙Ais [填空1]A and the phase angle of it is [填空2]degree;The value of B phase currentI˙Bis [填空3]A and the phase angle of it is [填空4]degree;The value of C phase currentI˙Cis [填空5]A and the phase angle of it is [填空6]degree.
答案：{"1": ["6.84"], "3": ["7.31"], "2": ["-27.4"], "5": ["1.97"], "4": ["168"], "6": ["56.6"]}
问题：The balanced three phase load is in delta connection in the figure. The line voltage of balanced three phase source isU˙AB=220∠0∘Vand the impedance of load isZ=20+j20Ω.Find:1) The active power absorbed by three phase load is P =[填空1] W;2) Measure the total power with two meters method. The connection of one meter is shown in the figure. The reading of another power meter isP2=[填空2] W.
答案：{"1": ["3630"], "2": ["2863"]}
问题：As the circuit shown in the figure, the line voltage of balanced three phase source isU˙AB=380∠30oV, the frequency of the source is f=50Hz. The total power of motor isPD=1.7kW,cosφD=0.8（inductive）. The impedance of balanced three phase load isZ=50+j80Ω（delta connection）.1) The line current isIl=[填空1]A.2) In order to make the power factor in source iscosφ=0.9, we connect a Y connection three phase capacitor parallel to the load. The capacitance parallel to the load isC=[填空2]μF.
答案：{"1": ["10.1"], "2": ["69.3"]}
问题：The circuit is shown in the figure. The currenti1,i2are given. Find the reading of ammeter (effective value).1)i1=102√sin314tA,i2=5A, the reading of ammeter (effective value) is [填空1]A.2)i1=102√sin314tA,i2=102√sin(628t+10∘)A, the reading of ammeter (effective value) is [填空2]A.3)i1=102√sin314tA，i2=52√sin(314t+36.9∘)A, the reading of ammeter (effective value) is [填空3]A.4)i1=102√sin314tA，i2=5+52√sin(314t+36.9∘)A, the reading of ammeter (effective value) is [填空4]A.
答案：{"1": ["11.2"], "3": ["14.3"], "2": ["14.1"], "4": ["15.2"]}
问题：The figure shows a low pass filter circuit. The inductanceL=32.5mH, the capacitanceC=10μF, and the resistanceR1=160Ω,R2=2kΩ. The source voltageu1=400+100cos3ωt−20cos6ωtVand the angular frequencyω=628rad/s. Suppose the voltage of load resistorR2asu2=A+k1cos(3ωt+φo1)+k2cos(6ωt+φo2)V(k1,k2&gt;0). Solve the coefficients in the expression:A=[填空1],k1=[填空2]φ1=[填空3]k2=[填空4]φ2=[填空5]..
答案：{"1": ["370"], "3": ["-91.4"], "2": ["32.8"], "5": ["59"], "4": ["2.83"]}
问题：As the circuit shown in the figure, the voltage of voltage source isuS=1202√sinωt+302√sin(2ωt−90o)V,R1=60ΩR2=R3=30ΩωL1=40ΩωL2=20ΩωM=20Ω1/(ωC)=80Ω.1) Define the current asi(t)=k12√sin(ωt+φo1)+k22√sin(2ωt+φo2)A(k1,k2&gt;0). Solve the coefficients in the expression:k1=[填空1]φ1=[填空2]k2=[填空3]φ2=[填空4]2) The reading of power meter is [填空5]W.
答案：{"1": ["1.44"], "3": ["0.353"], "2": ["-8.62"], "5": ["180"], "4": ["-118"]}
问题：As the circuit shown in the figure,uSis a sinusoidal ac source with angular frequencyω.U0is dc voltage.R1=1Ω,R2=2Ω,ωL=1Ω,1/(ωC)=4Ω. The reading of voltmeter is 10V and the reading of ammeter is 2A (both effective value). Find:1) DC source voltageU0＝[填空1] V and the mean power delivered by DC source isP1＝[填空2] W;2) The effective value of AC source voltage isUS＝[填空3] V and the mean power delivered by AC source isP2＝[填空4] W.
答案：{"1": ["18"], "3": ["11.7"], "2": ["108"], "4": ["52.5"]}
问题：以下关于机器学习的基本概念中说法错误的是： {'A': '机器学习是近20多年兴起的一门多领域交叉学科，涉及概率论、统计学、逼近论、凸 分析、算法复杂度理论等多门学科。', 'B': '人工智能大致分为三种学习方法，即基于规则的方法、经典的机器学习方法、基于表示的学习方法。', 'C': '机器学习包括专家系统', 'D': '数据挖掘可以认为是机器学习和数据库技术的交叉学科，数据挖掘主要利用机器学习来分析数据，利用数据库技术来管理数据。'}
答案：C
问题：以下属于大数据机器学习的特征的是： {'A': '与日俱增的数据量', 'B': '不断增加的网络模型及模型复杂度', 'C': '媲美甚至超越人类认知的准确度', 'D': '以上都是'}
答案：D
问题：经验风险最小化最优模型，当样本容量很小时，经验风险最小化学习可能会产生哪种现象？ {'A': '欠拟合', 'B': '过拟合'}
答案：B
问题：真正例率TPR的怎么计算？ {'A': 'TPR=TP/(TP+FN)', 'B': 'TPR=FP/(FN+FP)', 'C': 'TPR=(TP+FN)/TP', 'D': 'TPR=(TN+FP)/FP'}
答案：A
问题：在ROC分析中，分类器的性能曲线的理想状态是： {'A': '对角线（AUC等于0.5）', 'B': '越靠下越好（AUC趋近于0）', 'C': '越靠上越好（AUC趋近于1）'}
答案：C
问题：任意一条ROC曲线都有一条代价曲线与之对应，反之亦然。 {'true': '正确', 'false': '错误'}
答案：true
问题：感知机属于生成模型还是判别模型？ {'A': '生成模型', 'B': '判别模型'}
答案：B
问题：感知机不能学习异或XOR函数 {'true': '正确', 'false': '错误'}
答案：true
问题：多层感知机解决线性不可分问题的原理是： {'A': '分而治之，对原始问题空间进行划分', 'B': '将原始问题向更高维空间映射', 'C': '在输出层和隐含层之间形成非线性的分界面', 'D': '将原始问题在隐含层映射成线性可分问题'}
答案：D
问题：在感知机中（Perceptron）的任务顺序是什么？1随机初始化感知机的权重2去到数据集的下一批（batch）3如果预测值和输出不一致，则调整权重4对一个输入样本，计算输出值 {'A': '1, 2, 3, 4', 'B': '4, 3, 2, 1', 'C': '3, 1, 2, 4', 'D': '1, 4, 3, 2'}
答案：D
问题：以下关于感知机说法错误的是： {'A': '感知机是二分类的线性分类模型，属于非监督学习算法', 'B': '只要参数设置得当，感知机理论上可以解决各种分类问题', 'C': '感知机的训练过程可以看成是在误差空间进行梯度下降', 'D': '感知机学习算法是正确分类驱动的'}
答案：A, B, D
问题：聚类任务是有监督学习还是无监督学习？ {'A': '无监督学习', 'B': '有监督学习'}
答案：A
问题：距离度量需满足的基本性质有：非负性，同一性，对称性，直递性 {'true': '正确', 'false': '错误'}
答案：true
问题：DBSCAN是基于划分的聚类 {'true': '正确', 'false': '错误'}
答案：false
问题：关于因子图，说法错误的是： {'A': '因子图由两类不同的结点组成，且所有的链接都位于两类不同的结点之间', 'B': '基于因子图可以用和积算法高效的求各个变量的边缘分布', 'C': '和积算法是一种通用的消息传递算法', 'D': '只有无向图能转化为因子图'}
答案：D
问题：关于贝叶斯网络，说法错误的是： {'A': '贝叶斯网络是基于有向无环图来刻画属性之间的依赖关系的一种网络结构', 'B': '贝叶斯网表达了各个节点间的条件独立关系，我们可以直观的从贝叶斯网当中得出属性间的条件独立以及依赖关系', 'C': '结点间的相互独立关系会增加建网过程当中的计算量', 'D': '贝叶斯网可以处理不完整和带有噪声的数据集'}
答案：C
问题：朴素贝叶斯法属于生成模型。 {'true': '正确', 'false': '错误'}
答案：true
问题：朴素贝叶斯法没有明确的搜索可能假设空间的过程。 {'true': '正确', 'false': '错误'}
答案：true
问题：为什么需要半朴素贝叶斯分类器？ {'A': '后验概率P(c∣x)计算起来比较困难', 'B': '属性条件独立性假设在现实任务中往往很难成立。', 'C': '以上均正确', 'D': '以上均不正确'}
答案：C
问题：Gibbs采样收敛慢。 {'true': '正确', 'false': '错误'}
答案：true
问题：通常特征选择的准则是 [填空1]
答案：{"1": ["信息增益"]}
问题：逻辑斯谛回归模型学习时，对于给定的数据集，一般用哪种方法估计模型参数，从而得到逻辑斯谛回归模型？ [填空1]
答案：{"1": ["  极大似然估计法"]}
问题：逻辑斯谛回归模型学习时，对于给定的数据集，一般用哪种方法估计模型参数，从而得到逻辑斯谛回归模型？[填空1]
答案：{"1": ["极大似然估计法", "极大似然估计", "极大似然"]}
问题：常用的模型学习的最优化算法有？ {'A': '改进的迭代尺度法', 'B': '梯度下降法', 'C': '牛顿法', 'D': '拟牛顿法'}
答案：A, B, C, D
问题：在线性可分情况下，训练数据集的样本点与分离超平面距离最近的样本点的实例称为 [填空1]
答案：{"1": [" 支持向量"]}
问题：线性可分支持向量机：给定线性可分训练数据集，通过间隔（）为目标，求解相应的凸二次规划问题，从而学习得到的最优分离超平面，此时解是（）的。 {'A': '最大 不唯一', 'B': '最大 唯一', 'C': '最小 唯一', 'D': '最小 不唯一'}
答案：B
问题：凸优化的任何局部最优解就是全局最优解。 {'true': '正确', 'false': '错误'}
答案：true
问题：线性支持向量机通过软间隔最大化将线性可分问题扩展到线性不可分问题？ {'true': '正确', 'false': '错误'}
答案：true
问题：如果超平面参数w和b成比例地改变（超平面没有变），几何间隔会按此比例改变，而函数间隔不会。 {'true': '正确', 'false': '错误'}
答案：false
问题：关于支持向量机SVM，说法正确的是： {'A': '边缘(margin)是决策边界与任意样本之间的平均距离', 'B': '支持向量 (support vector) 位于最大边缘超平面附近的点', 'C': '分类间隔为1/||w||，||w||代表向量的模', 'D': '决策边界只会被支持向量影响，跟其他点无关'}
答案：D
问题：支持向量机是比核方法更为一般的机器学习方法。 {'true': '正确', 'false': '错误'}
答案：false
问题：研究无限维线性空间上的泛函数和算子理论，被称为（） [填空1]
答案：{"1": [" 泛函分析"]}
问题：SVM的效率依赖于： {'A': '核函数的选择', 'B': '核参数', 'C': '软间隔参数', 'D': '以上所有'}
答案：D